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Equipment Discussions >> Mounts

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Domerman
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Reged: 07/21/07

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Do direct drive mounts really not require guiding?
      #5709928 - 03/03/13 04:35 AM

So I'm looking to get a portable high-end mount for 10k or less that can haul perhaps something not much larger than a TEC 140. I want this mount pretty much only for AP, however, I will not have a permanent setup and will require a light mount that is not too difficult to setup. I really would love to avoid auto-guiding if possible and I was wondering if these new ASA mounts are as accurate as they really say? I understand that ultimately one will need to guide to eliminate for atmospheric abberations, but as far as mechanical corrections are concerned, the periodic error on these mounts is incredibly low. This is very exciting, as I would only need to focus on polar aligning and letting the scope do the rest. I know there are true and tested mounts out there in this class like AP and Paramount, however, these are for a lack of a better word...bulky and still require guiding and plate solving....or am I completely wrong in all of this?

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Footbag
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Re: Do direct drive mounts really not require guiding? new [Re: Domerman]
      #5710152 - 03/03/13 09:02 AM

Any mount that doesn't require guiding is going to require you to build up a pointing model. This takes a good amount of time, and isn't as conducive to a portable setup as one would hope.

I may be wrong about this, but it isn't really the direct drive technology as much as the encoders that can allow you to forgo guiding. The AP 1600 has absolute encoders. Maybe the 1100 will offer it, but I don't see the Mach 1 getting them soon.

For a permanent setup, I'd buy an ASA in a second. For portable, I'm thinking AP is the best option; just understand that you'll be guiding. I've worked my guiding routine into my PA setup and can probably get setup in 30m with them.


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: Footbag]
      #5710268 - 03/03/13 10:08 AM

Ray says that APCC will allow even non encoder AP mounts to shot unguided for tens of minutes. Its not the direct drive, its the pointing model.

That said a quick fix is to buy a standalone guider like an SG4 or a Lacerta MGEN. This would let you dispense with the PC.


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neptun2
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Reged: 03/04/07

Loc: Bulgaria
Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #5710950 - 03/03/13 04:30 PM

The direct drive means that you have no periodic error. This helps. The other high end mounts that are not direct drive have very low periodic error but there is some. Encoders can definitely help to avoid the need of guiding if they are very high precision but the ASA is for me the best combination of technology at one place. They have something called MLPT (Local multi precision tracking) which some kind of pointing model specific for the object that you will image. With this i do not see any reason to guide. See more details here:

http://www.astrosysteme.at/eng/software_mlpt.html

Also the ddm60 is definitely portable and relatively easy to setup from what i have read.


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Domerman
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Re: Do direct drive mounts really not require guiding? new [Re: neptun2]
      #5711228 - 03/03/13 06:55 PM

So what is a pointing model and can it eliminate the need for guiding? What do I need to make a pointing model?

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neptun2
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Reged: 03/04/07

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Re: Do direct drive mounts really not require guiding? new [Re: Domerman]
      #5711471 - 03/03/13 08:59 PM

The idea behind ASA's MLPT is that you tell the software which object you will image and how many and how long exposures you will take and after this the mounts points o the object, calculate how long it will travel the sky till the exposures are completed, takes several exposures during it's path, plate solve them and see exactly what kind of errors you will have while imaging. This allows later these errors to be corrected. This allows to compensate for practically all mechanical errors including flexure, mirror flop in SCTs and all other. That's why you do not need guiding.

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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: neptun2]
      #5711568 - 03/03/13 09:50 PM

Steve, TheSkyX can produce a good pointing model. Same for the ASA software and the upcoming APCC.

The key requirement is that your periodic error must be zero or pretty close to it. Then the pointing model only needs to compensate for flexure, mirror flop, atmospheric refraction, etc.

Now a worm-driven mount won't have zero periodic error, but the decent ones (Paramount, AP) can get the periodic error down to sub-1" (0.5" or thereabouts) peak-to-peak. So if you are imaging at say 2" / pixel (typical for a short to mid-FL refractor) then you don't need to guide because the periodic error is small enough.

Note that you still need the pointing model, long unguided exposures aren't just about having small (or zero) PE.

Ah - and, to use this pointing model, you need a PC with appropriate software. At this point the advantage of AP over Paramount ("you don't need a PC!") goes away, because you will need a PC to work this magic.

IMHO, a better solution is to just buy a stand-alone guider. After all the reason most people don't want to guide, is because they don't want to use a PC. The pointing model solutions all require a PC, so the only advantage is you're not subject to wind or clouds screwing the guide star.

But if your goal for not wanting to guide is convenience, having a PC along is not convenient.


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frolinmod
Carpal Tunnel


Reged: 08/06/10

Loc: Southern California
Re: Do direct drive mounts really not require guiding? new [Re: neptun2]
      #5711590 - 03/03/13 10:01 PM

@neptun2, that's cool. I like that. However, that does assume everything is 100% repeatable which is not always the case, particularly with SCT mirror flop. I consider all these cool schemes as being somewhat analogous to "PEC for tracking." They're quite helpful, but don't expect perfection. They may even be "good enough" for lower focal lengths or short exposures, but eventually you're probably going to need a guider. Might as well figure that into your plans from the beginning. These things do make the guider's job easier, allow it to make corrections less often, make longer exposures hence use dimmer guide stars, etc. Good to have for sure.

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Domerman
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Re: Do direct drive mounts really not require guiding? new [Re: frolinmod]
      #5711626 - 03/03/13 10:16 PM

Wait, but if I use a CCD, I will need a computer no matter what. I have no plans of using a DSLR. I want to use a mono camera with filters for narrow band imaging.

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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: Domerman]
      #5711627 - 03/03/13 10:18 PM

Err.. true. In which case I don't really see the benefit of no guiding. The hassle involved with setting up and building the pointing model VS not needing to find guide stars.

But if your situation is such that there is strong wind and you're losing guide stars, then imaging under such circumstances is going to be a challenge anyway.

Although that said the ASA mounts supposedly can also compensate for wind gusts. That's something they have over the encoder-less mounts.


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Domerman
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #5711634 - 03/03/13 10:22 PM

So if strong winds are not an issue, then I might as well go the much cheaper route and get a portable Mach1 mount or Temma or something along those lines and use a 50mm guide scope?

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Domerman
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Loc: PA
Re: Do direct drive mounts really not require guiding? new [Re: Domerman]
      #5711643 - 03/03/13 10:26 PM

Also, I'm not quite understanding, if the encoders are allowing for almost no PE, then why do I need to guide? I thought guiding was just for wind and PE inherent to a mount. What is this business about pointing models?

EDIT: I am guessing the encoders cannot account for flexure and things of that nature, thus is the reason you need pointing models. Answered my own question, I think..

Edited by Domerman (03/03/13 10:29 PM)


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: Domerman]
      #5711648 - 03/03/13 10:29 PM

Because sidereal rate isn't.

Due to atmospheric refraction at different elevations (altitude) the speed is not precisely the sidereal rate.

Also with an SCT, the mirror moves around as you point to different objects, causing image shift.

But in answer to your question... yes a good worm-drive mount and a guider is what I'd do. In fact that is what I have done. A guider calibrate only takes a short time, and the Mach1 is the lightest mount you can get that's decent.

I would stay away from the Temma if I were you... Taks are overpriced for what you get (no PEC! and the EM200 is only rated +/- 5" I think - so no way to get that down).

My Mach1 is about 3.5" p-p when east-heavy, and 6" p-p when west-heavy. PEM gets this down to 0.4" / 0.8".

You can't get anywhere close to 0.8" p-p with an EM200 because there's no PEC. Tak NJP (and I suppose EM400) can get about 1.5" p-p but those are heavy. An NJP is cheaper than a Mach1 if you can find one. But remember.. with Temma there's no GoTo from the handset. You need to command GoTo's from a computer.

And coming from a CGEM like I did... you will be amazed and shocked at the primitive mount modeling of AP and Tak. Only one-star aligns are supported, so your polar alignment has to be dead-on, otherwise GoTo's will be inaccurate.

but then again you need a dead-on polar alignment to image, so...


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Domerman
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #5711651 - 03/03/13 10:31 PM

Quote:

Because sidereal rate isn't.

Due to atmospheric refraction at different elevations (altitude) the speed is not precisely the sidereal rate.

Also with an SCT, the mirror moves around as you point to different objects, causing image shift.

But in answer to your question... yes a good worm-drive mount and a guider is what I'd do. In fact that is what I have done.




Oh ok! That makes perfect sense now!


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shams42
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Re: Do direct drive mounts really not require guiding? new [Re: Domerman]
      #5711683 - 03/03/13 10:50 PM

The Tak mounts are ideal for portable use, though, because of the uber-accurate polar scope. I can set up and polar align my NJP in less than 10 minutes and then shoot 20 minute subs all night long without losing a single one (autoguided, of course).

If I ever move to a more permanent setup I will probably get a Paramount MX. Until then, I really like the Tak.


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: shams42]
      #5711693 - 03/03/13 10:57 PM

The trouble with the new Taks is that they aren't palatable cost-wise. Paying almost the same money for an EM200 vs Mach1 just for the polar scope is... not good sense.

Of course a used Tak NJP has got to be the deal of the year, if you can find one. A new EM400 at $10400... not so much. You can get an AP1600 for that kind of money.


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korborh
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #5711715 - 03/03/13 11:13 PM

I have to say there is something quite elegant about the Tak mounts that they achieve such accurate performance with much smaller gears/bearings than AP/SB. And the polar scope is very nice calibrated from the factory. The price is too high unfortunately.

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Domerman
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Re: Do direct drive mounts really not require guiding? new [Re: korborh]
      #5711815 - 03/04/13 12:43 AM

So in the not to distant future I see myself using a Mach1GTO with a TEC 140 and auto-guider. I think the AP should be able to handle this load appropriately. I'm assuming my C11 for visual use would be well handled by the the Mach1GTO, as my CGEM handles it fairly well..

Is there any other portable GEM I should consider in this price range?

I really want to emphasize portability here...so the CGE Pro and similar are off the table.

Edited by Domerman (03/04/13 12:44 AM)


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: Domerman]
      #5711820 - 03/04/13 12:51 AM

The Mach1 will handle the C11 for imaging without any problems.

There simply isn't any other mount in that weight class (30 lb for the head) that can match the Mach1. The EM200 weighs more and carries less. I also looked at the CGE Pro for less money but it's very heavy. The G11 weighs more and is less capable. Not sure how much the ASA DDM60 weighs but it costs more. Ditto for the Paramount MX - more capacity, arguably better payload for the dollar, but also heavier. Tak NJP also quite heavy.

Well there is one alternative.. AP 1100 (the 900 replacement). Which weighs less than the 900. The 900 weighs 55 lb total and splits into two parts. Each part weighs a bit less than a Mach1.

So the question for you is.. what is lightweight? 30 lb? or pieces that weigh 30 lb?


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neptun2
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Reged: 03/04/07

Loc: Bulgaria
Re: Do direct drive mounts really not require guiding? new [Re: korborh]
      #5711821 - 03/04/13 12:53 AM

Well about the ASA MLPT - i read that people get 40 minute exposures at over 2000mm focal length so i don't think that it is usable only with short focal lengths. Another idea of the MLPT is that you don't need to create big pointing model when you use it. You make basic pointing model with several points so that you can make your polar alignment and goto accuracy is good but after that the MLPT creates local pointing model for the object that you will image. I always have laptop with me on the field so that is not a problem.

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frolinmod
Carpal Tunnel


Reged: 08/06/10

Loc: Southern California
Re: Do direct drive mounts really not require guiding? new [Re: neptun2]
      #5711844 - 03/04/13 01:20 AM

Quote:

i read that people get 40 minute exposures at over 2000mm focal length so i don't think that it is usable only with short focal lengths.



I consider 2000mm to be a short focal length. Also, I didn't say it was "usable only at short focal lengths." I'm certain it can be at least somewhat helpful at almost any focal length.


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Footbag
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Re: Do direct drive mounts really not require guiding? new [Re: neptun2]
      #5711845 - 03/04/13 01:21 AM

Quote:

Well about the ASA MLPT - i read that people get 40 minute exposures at over 2000mm focal length so i don't think that it is usable only with short focal lengths. Another idea of the MLPT is that you don't need to create big pointing model when you use it. You make basic pointing model with several points so that you can make your polar alignment and goto accuracy is good but after that the MLPT creates local pointing model for the object that you will image. I always have laptop with me on the field so that is not a problem.




How long does the MLPT take? And is it fully automated?


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neptun2
scholastic sledgehammer


Reged: 03/04/07

Loc: Bulgaria
Re: Do direct drive mounts really not require guiding? new [Re: Footbag]
      #5711887 - 03/04/13 02:36 AM

Well the information from ASA is that the mount software commands the camera (you should have ascm compatible camera for that) and it takes around 10 exposure alongside the path where the object will pass and plate solve them to make the pointing model. It looks like automatic process and it should not take so much time to take 10 exposures which can be plate solved.

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Waldemar
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Re: Do direct drive mounts really not require guiding? new [Re: neptun2]
      #5712158 - 03/04/13 09:41 AM

Maybe it is a smart move to go to the ASA site and download their manuals... that will give at least a bit of insight.
I find my ASA DDM60Pro to be an incredible piece of technique with far more outstanding features than just the possibility for unguided tracking. No guider camera can compensate for windgust for the simple reason guiding with a camera is far too slow, compensation is always after the fact. ASA corrects while it is happening... not after the fact, but realtime! I know of no other mount that can do that. It can also compensate for flexures like is said before, although I personally think that the set-up should be as rigid as possible to prevent flexing, but nevertheless.
Everything is so easy to do: balancing with electronic help from the AutoSlew program from Philip Keller, Setting the PID settings is automated as well, so is making pointing files. Still the software is different enough from others to challenge your intellect. Well... for me anyway...
Goto speeds and accuracy are simply beyond and silent!
My MicroTouch focusser makes alot more noise then my mount!
Now that I finally understand how I can make things happen, I need better weather and TIME!

just my 2c
Clear Skies for all and myself!


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Pak
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Reged: 09/15/12

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Re: Do direct drive mounts really not require guiding? new [Re: neptun2]
      #5712391 - 03/04/13 12:08 PM

I can't believe I am saying this out loud but...

It sounds like you should consider the LX850.



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GIR
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Reged: 01/02/10

Loc: Finland
Re: Do direct drive mounts really not require guiding? new [Re: Waldemar]
      #5713801 - 03/05/13 02:53 AM

Have to agree with Waldemar, ASA is simply an astonishing mount ...very fast, unbelievably accurate and silent. The only noise comes from the camera fans. I used to have G11 before and you can't really compare those two mounts.

Making a pointing model is easy and fast, especially if you plate solve using bin 3x3 to speed up the download time. Building a very accurate 50 point model takes about 15-20 minutes, depending on what kind of camera and computer you have.A 10 point MLPT takes couple of minutes.

However, you can actually use an old model even in the field because there is a special feature just to adjust the polar alignment with 3 points. Haven't tested it myself yet because I have a permanent set up. Anyway, you don't necessarily need a large pointing model if you're using the MLPT feature; 20 points should more than enough.

Making the ASA mount work properly requires some tuning, however most of it is very simple to do and has to be done only once.

ASA DDM60 Pro


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psandelle
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Reged: 06/18/08

Loc: Los Angeles
Re: Do direct drive mounts really not require guiding? new [Re: GIR]
      #5714457 - 03/05/13 01:16 PM

Quick question to the ASA mount guys & girls - after really looking it over, I think the term "unguided" is a bit misleading, in that the ASA software, in a way, does predictive guiding based upon real pics taken by the CCD and mount (plate solves, errors accounted for, etc.) - but it internally checks where it should be against the encoders, where a guidescope/OAG CCD setup checks against the external value of the star displacement. So, it is kinda "guided" - just in a different manner (it's not like you point the mount at an object and let 'er run and it somehow "magically" stays on the target - it solves and predicts where to be).

Anyway, that being the case, have any of you figured which was more accurate, an external/OAG guided ASA mount versus the ASA software's "internal" method of guiding? I mean, both methods have error, I would think. If there were some numbers that said that the ASA software/plate solving method was more accurate than a guider, that'd be interesting. And, yes, I understand people are getting 20+ minute "unguided" subs on the ASA's, but was curious if those 20+ subs were better or worse, analytically, than the same mount/scope with a guidescope/OAG.

Thanks, just curious,

Paul


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elbee
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Reged: 05/02/09

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Re: Do direct drive mounts really not require guiding? new [Re: psandelle]
      #5714491 - 03/05/13 01:30 PM

for those of you that have/use an ASA mount i have a question. i have seen MLPT work, and it works extremely well without guiding (10-15min subs and modest FL), BUT from what i have observed, the MLPT model can not handle a meridian flip. you build the MLPT model either before or after the meridian flip. so how do you run an automated session (i.e., ccdautopilot, acp, etc) without having to be there to rebuild an MLPT model following a meridian flip?

EDIT: one other "problem" i have seen with MLPT within an automated session. the MLPT model will not easily account for time taken out to do refocus runs. MLPT seems to rely very heavily on knowing where the object is in the sky within a time interval t(start) to t(finish). if it is not where it is supposed to be (because some time was taken to do a temperature dependent - unexpected - focus run), things don't go so smoothly.

thanks

Edited by elbee (03/05/13 02:10 PM)


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blueman
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Reged: 07/20/07

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Re: Do direct drive mounts really not require guiding? new [Re: neptun2]
      #5714494 - 03/05/13 01:31 PM

Guiding is not difficult and it is not that expensive either. If you are imaging, well you have everything but the guide camera and scope anyway. Most acquistion software will guide, so there is not that much extra effort to guide in my opinion.
Blueman


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psandelle
professor emeritus


Reged: 06/18/08

Loc: Los Angeles
Re: Do direct drive mounts really not require guiding? new [Re: blueman]
      #5714511 - 03/05/13 01:37 PM

blueman - I don't think guiding's tough, either (or expensive, or whatever people say), but in looking closer, I realized that the ASA software is doing something akin to guiding anyway, but I don't know how accurate compared to "external" guiding methods. Was curious.

Also, if you're using the ASA method, would external guiding be superfluous if the ASA method were more accurate.

Paul


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SL63 AMG
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Reged: 12/21/09

Loc: Williamson, Arizona
Re: Do direct drive mounts really not require guiding? new [Re: psandelle]
      #5714581 - 03/05/13 02:24 PM

Being the owner of a DDM85, I will agree with everything said by the other owners of ASA DDM mounts.

I first owned a DDM60 prior to them putting fixed encoders on each axis and I didn't like the setup. I still don't like the tip tilt system of the base plate for polar adjustments.

The DDM85 offers a much better method where the base plate rotates for RA and the DEC axis is lifted by a hand wheel.

That being said, setting up the DDM85 for portable use isn't an issue. I set mine up in my driveway every month. I used a sharpie to mark the positions of the tripod feet and this gets my polar alignment to within a few arc minutes each setup.

I could image 5-10 minute subs easily with a polar misalginent under 5 arc minutes, but I am rather anal and won't accept anything less than 0.5' of error and I almost always achieve 0.3' (<= 18") or better.

In order to get this accurte of polar aligment usually requries me to shoot 3 autopoint files of 10-15 stars on one side of the mount, then go find a star on the southern meridian near my latitude, center it on my CCD chip, instruct Autoslew to make a polar correction and then manually dial the star back onto the center of the chip.

This used to take some time with my QSI583wsg because the camera download time is slow, but with my FLI ML8300 combined with connecting my mount to MAxim for telescope control, I can knock out polar adjustment in about 10 minutes, so chalk up about 30-40 minutes for a very accurate polar alignment.

Once my polar alignment is complete, I make a 50 star pointing model with 25 stars on each side of the mount. This takes about 15 minutes. The accurate pointing model corrects all left over polar alignment error, collimation error, mount angle error offset constant and applies a fourrier correction. About the only thing no corrected for is Hysterisis, which all telescope systems exhibit to some degree or another.

Once corrected, I go to my object, synch my plate solving program Sequence (also used for polar alignment and pointing model) and then I start MLPT.

MLPT is a unique tool. Basically, you tell it how long is your total exposure time for all subs, how long each sub is and then tell it to go. It shoots a sub at each point along the arc of the object and plate solves the image, then calculates where it is in the sky versus where it should be in the sky. MLPT then makes corrections during the entire image run keeping the system on track, corecting for all of the items I listed above.

I have discovered through much trial and error that it is best to keep your points small. In other words, if I am shooting 10 minutes subs for 100 minutes, instead of telling that to MLPT, I get better results telling it to run MLPT ar 100 minutes for 5 minutes usbs forcing it to shoot 20 points along the arc.

Anyway, it works as advertised. I have taken up to 30 minute unguided subs at 900mm FL F/3.6 and up to 15 minute subs at 2432mm FL at F/8.

As elbee stated, there are some drawbacks and I am now trying to leanr how to guide the mount for long narrowband exposures at 2432mm FL.

Two of the disadvantages of MLPT are that you cannot leave the MLPT run to go autofocus, such as during a temperature change, and you cannot image to the meridian, flip, then start again without executing another MLPT routine, which is a user intervened process.

The mount can be commanded for automatic meridian flips, but then you lose MLPT.

This is anothe reason I see autoguiding useful for long exposures.

A benefit of the ASA mount for autoguiding is the fact there is no periodic error and there is no backlash.

The optical encoders on the DDM85 are accurate to .02" which is quite incredible.

I could go on and on about the mount, but suffice it to say it is accurate, it does work as advertised and I wouldn't trade mine for any other mount. I might one day get another mount, like an AP or Paramount, mostly to learn something new, but I would not give up my ASA ot get one of these even with the MLPT issue.

I believe Dr. Keller will one day script MLPT so that it can be controlled by ACP and CCDAutoPilot. There is no reason not to as it takes only a few parameters.

Once MLPT can be scripted, one can script an MLPT run for any lenght of time, interrupt it, go focus, do a meridian flip, whatever, then come back and initial another MLPT and start imaging again.

By the way, the time it takes to do MLPT varies based upon the length of your total exposure time, number of exposures and the length of your plate solve exposure.

For most of my MLPT runs, setup is 5-8 minutes. Once can also increase the MLPT iterations for better accuracy, such as when shooting low in the southern sky.

I have to go take my friend to the airport. I may write more later if I can think of anything worth posting.



My physical setup time is about two hours, which I do during the day.


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psandelle
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Reged: 06/18/08

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Re: Do direct drive mounts really not require guiding? new [Re: SL63 AMG]
      #5714693 - 03/05/13 03:26 PM

Dave - great summation about everything. I now have a much better understanding of how it all fits together (MLPT, guiding, etc.). Very cool. As I move forward over the years, I'll keep this in mind on picking my next mount.

Paul


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Per Frejvall
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Re: Do direct drive mounts really not require guiding? new [Re: neptun2]
      #5719782 - 03/08/13 01:53 AM

I've test shot a 1-hour sub at M106 with a 190MN mounted on my 10Micron GM2000HPS - unguided. The mount keeps the pointing model in-mount, so once you have a model you actually don't need the PC per se.

I recently added a GM1000HPS as the GM2000HPS is going away to a remote site in Southern France, and that little bugger looks very promising.

If unguided is your aim, 10Micron mounts may be a good choice.

/per


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jjongmans
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Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #5719822 - 03/08/13 03:30 AM

I'm using an ASA DDM60 in a permanent setup. The performance is outstanding. I could achieve 30 min. unguided subs on the first night using it. I ran an automated three-star-polar-alignment-pointing-model, did an accurate polar alignment. I don't use MLPT, but I use an all-sky model with 50 points, also automatically created. After that I could take 30 min. subs with a focal length of 2000mm.

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TerraPassenger
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Re: Do direct drive mounts really not require guiding? new [Re: jjongmans]
      #6303731 - 01/10/14 09:09 AM

I'm thinking about purchasing a ASA DDM60 Pro. However, I will need to use this mount in a portable configuration - setting it up and then tearing it down each night.

I'm wondering, how long does it take to set up the ASA DDM60 Pro in the field? Assume that the setup location is new - one that you've never visited before.

I'm interested in the DDM60 Pro but based on what I've read, field setup may be quite a bit longer than for other mounts.

Thanks in advance for your help.

Dave


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Waldemar
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Re: Do direct drive mounts really not require guiding? new [Re: TerraPassenger]
      #6304487 - 01/10/14 03:32 PM

did you not read this thread?

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rmollise
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Re: Do direct drive mounts really not require guiding? new [Re: Footbag]
      #6304563 - 01/10/14 04:25 PM

Quote:

Any mount that doesn't require guiding is going to require you to build up a pointing model.




Not really. a pointing model might or might not be required, but it has nothing to do with the mount's lack of periodic error or drive system. It has to do with the go-to alignment system used.


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TerraPassenger
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Reged: 12/26/13

Re: Do direct drive mounts really not require guiding? new [Re: rmollise]
      #6304692 - 01/10/14 05:39 PM

>> did you not read this thread?
Yes, I did.

For the user who pre-marked his DDM85 location on his driveway it sounded like 30-40 minutes for polar alignment, followed by 15 min for a 50 star point model followed by 5-8 min (times 2? if a meridian flip is needed) for a MLPT which is 30+15+2*10=65 min.

The reason I've restated the question is to confirm the above estimate.


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jrcrillyAdministrator
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Re: Do direct drive mounts really not require guiding? new [Re: rmollise]
      #6304759 - 01/10/14 06:19 PM

Quote:

Quote:

Any mount that doesn't require guiding is going to require you to build up a pointing model.




Not really. a pointing model might or might not be required, but it has nothing to do with the mount's lack of periodic error or drive system. It has to do with the go-to alignment system used.




For unguided imaging at most focal lengths a pointing model will, indeed, be required to compensate for things like declination drift, flexure, and atmospheric refraction. Without a closed loop from a guider, those can only be derived from a model.


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rmollise
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Re: Do direct drive mounts really not require guiding? new [Re: jrcrilly]
      #6305039 - 01/10/14 09:26 PM

A pointing model won't do a thing for declination drift. A T-point assisted polar alignment will. The go-to alignment doesn't do squat for tracking.

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Odell
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Re: Do direct drive mounts really not require guiding? new [Re: rmollise]
      #6305043 - 01/10/14 09:32 PM

Or:

http://www.siderealtechnology.com/


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frolinmod
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Re: Do direct drive mounts really not require guiding? new [Re: rmollise]
      #6305087 - 01/10/14 10:02 PM

Quote:

The go-to alignment doesn't do squat for tracking.



It makes a big difference here with my EdgeHD 14 and Paramount ME with ProTrack enabled and active. So much so that I would never want to image without it.


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jrcrillyAdministrator
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Re: Do direct drive mounts really not require guiding? new [Re: frolinmod]
      #6305108 - 01/10/14 10:17 PM

Quote:

Quote:

The go-to alignment doesn't do squat for tracking.



It makes a big difference here with my EdgeHD 14 and Paramount ME with ProTrack enabled and active. So much so that I would never want to image without it.




ProTrack was probably the first such solution offered to the amateur market. A number of other high-end manufacturers have since implemented such systems. Sounds like a great idea to me!

Earlier implementations of auto dec corrections (Meade's dec drift training and the Vixen SS2K's dual axis tracking) were much less effective.


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GIR
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Re: Do direct drive mounts really not require guiding? new [Re: TerraPassenger]
      #6305473 - 01/11/14 04:08 AM

Quote:

>> did you not read this thread?
Yes, I did.

For the user who pre-marked his DDM85 location on his driveway it sounded like 30-40 minutes for polar alignment, followed by 15 min for a 50 star point model followed by 5-8 min (times 2? if a meridian flip is needed) for a MLPT which is 30+15+2*10=65 min.

The reason I've restated the question is to confirm the above estimate.




Dave

The time needed setting up any system is very much dependent on the person who is doing it and what kind of setup he has.

Harel is settting up his system in 30 min (look at the CCD imaging thread) Somebody else might require more time. I'm having a permanent setup so can't give you a definite answer. However, have taken the system down and set it up so many times that should be able to do it in 30 min in any place.

P.S. DDM60 has a built in laser which is VERY helpful when doing the first rough polar allignment. Only people who don't have it say you'll not need it. Besides polar allignment with ASA mounts will take far less time than 30-40min.


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Waldemar
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Re: Do direct drive mounts really not require guiding? new [Re: GIR]
      #6305759 - 01/11/14 09:37 AM

Rough PA takes me less than a minute with the laser on my DM60Pro
It is done with the ďnakedĒ Mount, without scope or weights
For balancing I made marks and stops on the dovetail, depending on what camera and setting I use. so that does not take very long either. PID settings are previously done for different set-ups and stored in the software, as are the pointingfiles. You can make a set of pointingfiles for different areas in the sky as well as in the world and store them for later use. Next step will be "go-to" a star at app. the same altitude, but in the Southern sky to align with, center it with the AltAz adjustment (tilt) screws, enter....ready to go in let's say 10 min, after initial set up of tripod and Mount with scope.
The accuracy, speed, stillness and capability of this mount is totally unbelievable until you have experienced it yourself... This DDM60Pro is the best piece of equipment that ever happened to me.
After the initial brainfarts from my side and the for me rather steep learning curve , I can truly say that this is premium high end hard- and software.
As far as guiding goes: guiding with cameraís is always seconds too late doing the corrections. The DDM checks realtime 100 times per second between the "IS" and the "SHOULD BE" position, and corrects accordingly. This of course is done without optics, by comparing absolute decoder positions (0,02" accurate !!).
So however well you may be able to guide, you are just always too late: after the fact... seconds!
NO back-lash, NO PE, If you need really accurate tracking, just use a 3 star polar-alignment, that will take a few minutes longer
With DDM your scope is directly connected to the motor axes without any gearing in between. Think of that: how incredible is it to construct a powerful motor making 1 rev per 24 hours ...

So... just for what it is worth.

Regards, Waldemar


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TerraPassenger
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Reged: 12/26/13

Re: Do direct drive mounts really not require guiding? new [Re: Waldemar]
      #6305818 - 01/11/14 10:08 AM

Thanks very much for the time estimates for portable setup.

There's a few youtube videos - including this one by Harel http://www.youtube.com/watch?v=GULVyAinFKA - showing how amazingly fast and quiet the DDM60 is. One of the few drawbacks I've heard is that the mount is hard to set up in the field; perhaps so, but it sounds like once you've mastered the basics of setup, remote setup of the DDM60 isn't too much different than for other mounts.

And - a minor thing - I really like the red color of the mount! Paired with the OS Veloce RH 200, it makes quite a pleasing package.

Edited by TerraPassenger (01/11/14 10:11 AM)


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GIR
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Re: Do direct drive mounts really not require guiding? new [Re: TerraPassenger]
      #6305896 - 01/11/14 10:44 AM

Quote:


And - a minor thing - I really like the red color of the mount! Paired with the OS Veloce RH 200, it makes quite a pleasing package.




Will certainly agree with that statement

P.S. paying a bit extra for the Pro version is absolutely worth it. ASA mounts slew so fast and quiet that you don't want all kinds of cables hanging around in the dark.
See the difference on my Flickr page by comparing ASA DDM60 Pro and Losmandy G11 setups.


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Waldemar
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Re: Do direct drive mounts really not require guiding? new [Re: GIR]
      #6306042 - 01/11/14 11:48 AM

I think everything paired with this mount makes a very pleasing package!
And yes, it takes a bit of effort to find your way through the software, but what a reward!
, Waldemar


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WadeH237
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Re: Do direct drive mounts really not require guiding? new [Re: rmollise]
      #6309817 - 01/13/14 09:17 AM

Quote:

A pointing model won't do a thing for declination drift. A T-point assisted polar alignment will. The go-to alignment doesn't do squat for tracking.




A pointing model by itself won't.

But many of the solutions that use a pointing model also correct for declination drift. As mentioned, Pro Track does. So will the upcoming APCC Pro. I believe that the 10Micron mounts also use the pointing model to correct for declination drift.


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Per Frejvall
sage


Reged: 09/28/12

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Re: Do direct drive mounts really not require guiding? new [Re: WadeH237]
      #6310632 - 01/13/14 04:39 PM

10Micron mounts use a complex term model with up to 100 underlying points. The calculation result in a number of complex terms that model the sky.

The model is used for pointing and tracking. Tracking takes place in both Ra and Dec, so it is not merely compensating for declination drift.

/per


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Destrehan Dave
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6494240 - 04/28/14 04:29 PM

It's one year later... where's APCC?

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Ray Gralak
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Reged: 04/19/08

Re: Do direct drive mounts really not require guiding? new [Re: Destrehan Dave]
      #6494780 - 04/28/14 09:39 PM

Quote:

It's one year later... where's APCC?




The beta testing has been centered around validating the mount firmware to make sure no additional bugs are present. I think AP wants to be sure of that as it's really expensive to make the firmware chips that would be required if a bug is found.

APCC itself has been working for a long time, although development hasn't been idle. I have been making improvements at the suggestions of the beta testers.

-Ray


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frolinmod
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Reged: 08/06/10

Loc: Southern California
Re: Do direct drive mounts really not require guiding? new [Re: Ray Gralak]
      #6495205 - 04/29/14 05:06 AM

Hey, this is A-P. Get on the waiting list and maybe in 10 years or so... Just kidding!!!

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Hilmi
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Re: Do direct drive mounts really not require guiding? new [Re: frolinmod]
      #6495614 - 04/29/14 11:37 AM

A friend of mine complained his ddm60 is a power hog making it impractical for field use

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psandelle
professor emeritus


Reged: 06/18/08

Loc: Los Angeles
Re: Do direct drive mounts really not require guiding? new [Re: Hilmi]
      #6495648 - 04/29/14 11:48 AM

Hilmi - really? Is that the standard one. or Por? I've never heard that (seems ASA puts it at 0,4 - 0,8 Ampere - up to 3 Ampere). Hmm....

Paul


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Hilmi
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Re: Do direct drive mounts really not require guiding? new [Re: psandelle]
      #6497328 - 04/30/14 01:52 AM

I had asked Chris Hendren of OPT about his experience with the mount, he has been using the DDM60 Pro for some time. When I was considering upgrading my mount I contacted him by email and asked him how he finds it since it has been a long time since he posted the review on the website.

He said that for remote site use, he finds it takes too long to set up and that the amount power used was very high. He still likes his mount, but he says he is now considering putting it in a permanent setup and buying a different mount for mobile use.


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psandelle
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Reged: 06/18/08

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Re: Do direct drive mounts really not require guiding? new [Re: Hilmi]
      #6497856 - 04/30/14 11:08 AM

Bummer. I'll have to give him a call when it's time to buy. I was hoping the DDM60 Pro would be the final word for my mobile mount acquisitions. Hmmm....

Thanks,

Paul


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: psandelle]
      #6498054 - 04/30/14 01:02 PM

10micron seems to be the best deal at the moment. If I were buying today I'd get one.

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timmbottoni
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6498166 - 04/30/14 01:53 PM

Quote:

10micron seems to be the best deal at the moment. If I were buying today I'd get one.




I tend to agree with this as well. The biggest reasons would be that you don't need to guide, and you don't need a computer for anything.

That seems quite appealing to me, especially in Winter here.

Timm


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orion69
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Re: Do direct drive mounts really not require guiding? new [Re: timmbottoni]
      #6498429 - 04/30/14 03:59 PM

Quote:

...and you don't need a computer for anything.




How about for everything else? Controlling camera, filter wheel, focusing, framing, etc.
And if you want 30 min subs, why risk shooting unguided, it makes no sense.
If you're into AP, imaging without computer is like processing images with Paint.


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Hilmi
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Re: Do direct drive mounts really not require guiding? new [Re: orion69]
      #6499459 - 05/01/14 01:12 AM

Orion,

There are a lot of people out there who image using nothing but a DSLR and a timer remote and they are very happy with the results.

I do both guided CCD shots and unguided DSLR shots. Each has it's apeal. Let's just agree that some people find the prospect of imaging without a computer appealing and that some others don't understand why this is appealing. It is possible to image without a computer depending on the type of imaging you do. As to why risk unguided, it's not a risk if you know it works.

On my trips to dark skies, my setup that needs a computer keeps on failing on me due to the extra power requirements, on the other hand, my setup that uses nothing but a polarie mount and DSLR has consistently worked without fail.

So the ASA mounts have very good tracking, and maybe even better tracking than the 10 Micron, while on the other hand the 10 Micron mount has the advantage of being able to operate without a computer. Let's agree that these are both good points and that the decision on which one is better actually depends on the individual persons preferences.


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Per Frejvall
sage


Reged: 09/28/12

Loc: Saltsjöbaden, Sweden
Re: Do direct drive mounts really not require guiding? new [Re: orion69]
      #6499464 - 05/01/14 01:24 AM

Orion,

I disagree... There is more "risk" in guided imaging than there is in unguided - one less thing that can go wrong.

/per


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freestar8n
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Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #6499562 - 05/01/14 03:20 AM

Quote:

There is more "risk" in guided imaging than there is in unguided - one less thing that can go wrong.




That assumes the sky model is perfect and there are no external factors to shift the optic axis. If there are - then there are many "things" that can go wrong unguided - and the encoders wouldn't have a clue about them.

The basic test for me would be a large aperture system at about 0.5" per pixel with 20m narrow band image at a site with good seeing. The fwhm in a guided image without encoders can be perhaps 1.8". In that regime - can unguided do the same? In a mobile setup, how long does it take to get a sky model that will be adequate for that task? Does unguided work as well with inexpensive but well corrected sct's such as EdgeHD14?

Frank


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Tonk
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Re: Do direct drive mounts really not require guiding? new [Re: orion69]
      #6499714 - 05/01/14 08:07 AM

I'm perfectly happy using a DLSR camera with intervalvometer to control exposure duration and frame repetition and consequently I have a set up that doesn't need a separate computer. The DSLR camera saves results to its on board SD card. The setup doesn't use a filter wheel and it doesn't need a motorised focuser. The mount controls itself without an external computer.

Why do I do it this way. Well I live on a very cloudy island (UK) and I specialise in shooting one-offs with comets posing next to DSO's etc. I spend quite some effort researching likely clear sky locations within 100 mile radius - occasionally further. For this reason I have devised a set up that is fully mobile out of the back of a car - 10 Micron 1000HPS/TV 85 scope/Canon 450D; takes 20 to 30 minutes to setup and get high accuracy polar alignment via the mount controller and delivers 10 minutes unguided exposures without fuss (no dropped frames for 1 year now). The locations I use most - Pately Moor, Forest of Bowland and Sutton Bank - are remotish locations on top of hills with no power outlets etc so I keep it simple and low power using a set of Yuasa sealed lead batteries to power mount and camera and if needed a heater strip for the scope lens.

My earlier mobile set up used a Lomandy GM8/Gemini but unguided was limited to 4 - 5 minutes with lots of dropped frames on many occasions. I looked into computer guiding this set up about 6 years ago but it turned out then too clumbersome (computer) and risky - needing too much personal attendance (I like to get some sleep in the car once everything was going!). Hence my upgrade route last year was to get a mount that could track unguided for much longer and had the same setup ease as the Losmandy PAC procedure.

I also have a permanent pier outside my trailer near the Yorkshire Dales - there I do use a laptop computer and a host of other gismos because I have plenty of power and comfortable quarters.


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orion69
scholastic sledgehammer


Reged: 05/09/10

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Re: Do direct drive mounts really not require guiding? new [Re: Hilmi]
      #6499921 - 05/01/14 10:03 AM

Quote:

Orion,

There are a lot of people out there who image using nothing but a DSLR and a timer remote and they are very happy with the results.

I do both guided CCD shots and unguided DSLR shots. Each has it's apeal. Let's just agree that some people find the prospect of imaging without a computer appealing and that some others don't understand why this is appealing. It is possible to image without a computer depending on the type of imaging you do. As to why risk unguided, it's not a risk if you know it works.

On my trips to dark skies, my setup that needs a computer keeps on failing on me due to the extra power requirements, on the other hand, my setup that uses nothing but a polarie mount and DSLR has consistently worked without fail.

So the ASA mounts have very good tracking, and maybe even better tracking than the 10 Micron, while on the other hand the 10 Micron mount has the advantage of being able to operate without a computer. Let's agree that these are both good points and that the decision on which one is better actually depends on the individual persons preferences.




I agree with everything you said.

I expressed my point of view and of course others have different preferences.

What I'm saying is that if you have top class mount with absolute encoders, why limit yourself with poor camera like DSLR which is completely inferior to mono CCD?
Just because you don't want to use PC?
Money is obviously not in question because top class mounts are very expensive so if someone can buy ASA or 10micron I presume one can also buy mono camera and good battery if shooting mobile.

But if one is satisfied with that combination, OK by me.


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: orion69]
      #6500094 - 05/01/14 11:32 AM

I second Tonk. Over here clouds can ruin your evening very quickly. Things are such that I inevitably decline invites for 2-3 hour observing sessions from my group because it's not worth the effort to haul out all the gear, polar align, etc.

As for Frank's point, I'm fairly sure the 10Micron won't handle long exposure unguided with a moving mirror long FL scope well. But that's a very demanding use case.

Any technology that makes the common use case - short refractor - easy, is welcome.


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Tonk
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6500138 - 05/01/14 11:58 AM

Quote:

why limit yourself with poor camera like DSLR which is completely inferior to mono CCD?




Yeah - OK for a (semi) permanent setup. I'm getting a CCD next year BUT I wont be using that for my mobile runs.

Also how much more inferior is a DSLR to a CCD these days? Its not orders of magnitude as I can often produce better images with my DSLR than my local astro club friends can with their swanky CCDs


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: Tonk]
      #6500160 - 05/01/14 12:19 PM

For long, long narrowband subs, certainly the CCD is better. No contest. But that's my balcony activity. When I go to a dark sky site, I don't do narrowband if I can help it. And it would be at dark sky sites that quick setup and a DSLR are handy..

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psandelle
professor emeritus


Reged: 06/18/08

Loc: Los Angeles
Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6500197 - 05/01/14 12:42 PM

If the 10Micron had a USB & power hub in the Dec axis, I'd be all over that. I know it seems trivial, but I hate hanging cables. Sigh. I will have to give the ASA further inspection, as I hadn't heard others have power-sucking problems before.

Paul


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timmbottoni
Carpal Tunnel


Reged: 08/25/05

Loc: W Chicago suburbs, IL USA
Re: Do direct drive mounts really not require guiding? new [Re: orion69]
      #6500374 - 05/01/14 02:02 PM

Quote:

Quote:

...and you don't need a computer for anything.




How about for everything else? Controlling camera, filter wheel, focusing, framing, etc.
And if you want 30 min subs, why risk shooting unguided, it makes no sense.
If you're into AP, imaging without computer is like processing images with Paint.




My reasons are...
1) I image only with a DSLR right now, with a timer that can take images of any length I want, automatically once I set it and forget it
2) We have this thing called Winter here, and I want to be able to get setup, and go inside, and I don't want to leave a laptop sitting outside in the cold weather guessing whether it is autoguiding or not, or whether the cold will wreck it.
3) With my light pollution I could never get a 30min sub, heck I don't think I could get a 10min sub. If I image at 30 sec and at ISO 1600 without the new CLS EOS filter I got, it is already saturating the image with light pollution.
4) I know, I live in a horrible area for doing this, so whenever I decide to get serious, I will want something that is also portable enough to move or take around, and want to limit what I have to take into "the field" where ever that might be

I could be totally nuts, but that is why I think not needing a laptop is awesome.

Timm


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Edd Weninger
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Re: Do direct drive mounts really not require guiding? new [Re: timmbottoni]
      #6500457 - 05/01/14 02:42 PM

The newer DSLRs such as the Canon 6D full frame do some good stuff nowadays. Here's an example:

click for full resolution if you have a good monitor

http://www.pampaskies.com/gallery3/Deep-Space-Objects/M8_NGC6559_lowres

Cheers,


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Ray Gralak
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Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6501436 - 05/01/14 11:01 PM

Quote:

Quote:

There is more "risk" in guided imaging than there is in unguided - one less thing that can go wrong.




That assumes the sky model is perfect and there are no external factors to shift the optic axis. If there are - then there are many "things" that can go wrong unguided - and the encoders wouldn't have a clue about them.

The basic test for me would be a large aperture system at about 0.5" per pixel with 20m narrow band image at a site with good seeing. The fwhm in a guided image without encoders can be perhaps 1.8". In that regime - can unguided do the same? In a mobile setup, how long does it take to get a sky model that will be adequate for that task? Does unguided work as well with inexpensive but well corrected sct's such as EdgeHD14?

Frank



Sure that can be done. Here's a few with a 20 inch scope done by Wolfgang Promper:

http://www.astro-pics.com/142plm.htm
http://www.astro-pics.com/7129plm.htm
http://www.astro-pics.com/4725plm.htm
http://www.astro-pics.com/42ofm.htm
http://www.astro-pics.com/51ofb.htm

There's many more examples on his site. The trick in doing high resolution unguided imaging is to have a really good model, great seeing, and equipment with very predictable pointing and smooth tracking (most mid-range and low-end mounts are not in this category).

An even easier way is to do a PEMPro run and watch the graphs in RA and Dec. They should both be very flat over a long period of time and you don't really need to measure FWHM to see if tracking is dead on or not. An out of round star, for instance, could be from coma or astigmatism.

Also, rather than stating some arbitrary FWHM number like 1.8 arc-secs you really need to compare the median FWHM of many short exposures to the FWHM you get in a long exposure. Different scopes and sites will result in different levels of performance. On great seeing nights with a 12" scope it's not impossible to get low 1" arc-sec range for several minute exposures, but on another night no better than 3 arc-seconds with the same scope.

-Ray


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frolinmod
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Re: Do direct drive mounts really not require guiding? new [Re: Ray Gralak]
      #6501688 - 05/02/14 03:31 AM

Quote:

Sure that can be done. Here's a few with a 20 inch scope done by Wolfgang Promper



I'll bet that 20 inch scope is far more rigid than an EdgeHD 14, which was mentioned in the post you replied to. The EdgeHD 14 flops around like a pancake. With that particular OTA an off-axis guider is needed for images over 5 minutes or so even with well modeled a world class mount. It's not the mount in this case, it's the OTA.


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timmbottoni
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Re: Do direct drive mounts really not require guiding? new [Re: frolinmod]
      #6503938 - 05/03/14 11:16 AM

If the 10Micron builds a model of the sky, and is set up in a permanent set up, would you ever need to remodel the sky? In other words, does it ever have to be realigned or modeled to different stars as the sky changes through out the seasons?

Thanks,

Timm


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Raginar
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Re: Do direct drive mounts really not require guiding? new [Re: timmbottoni]
      #6504120 - 05/03/14 01:01 PM

If you move your mount, you have to re-model. But if you're permanently mounted? No, there isn't a requirement for it to be re-done. Of course, as you re-mesh, re-grease, etc.. you'd probably want to do it from time to time. Just like PEC.

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Per Frejvall
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Re: Do direct drive mounts really not require guiding? new [Re: Raginar]
      #6506592 - 05/04/14 07:59 PM

As the model has nothing to do with stars and instead models the errors of the mount there is no need to redo it except, as correctly stated above, when you mechanically change something on the mount/telescope.

/per


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timmbottoni
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Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #6506890 - 05/04/14 11:28 PM

Quote:

As the model has nothing to do with stars and instead models the errors of the mount there is no need to redo it except, as correctly stated above, when you mechanically change something on the mount/telescope.

/per




Thanks! That is what I was wondering. So you could build a model, move the mount and then what would you have to do? Just do a realign and start imaging?

Timm


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Per Frejvall
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Re: Do direct drive mounts really not require guiding? new [Re: timmbottoni]
      #6507439 - 05/05/14 09:54 AM

Quote:

Quote:

As the model has nothing to do with stars and instead models the errors of the mount there is no need to redo it except, as correctly stated above, when you mechanically change something on the mount/telescope.

/per




Thanks! That is what I was wondering. So you could build a model, move the mount and then what would you have to do? Just do a realign and start imaging?

Timm




I doubt you could move the mount to a new position and re-use the model. On the other hand, building a model is a non-issue with a PC and a slightly more tedious but still non-issue without a PC.

/per


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timmbottoni
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Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #6507531 - 05/05/14 10:46 AM

Thanks Per,

And I would love to read a comparison review between the GM1000HPS and the GM2000HPS. Besides weight capacity, are there any other signficant differences?

Thanks,
Timm


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EFT
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Re: Do direct drive mounts really not require guiding? new [Re: timmbottoni]
      #6507557 - 05/05/14 11:06 AM

Quote:

Thanks Per,

And I would love to read a comparison review between the GM1000HPS and the GM2000HPS. Besides weight capacity, are there any other signficant differences?

Thanks,
Timm




There are no significant differences between the GM1000HPS and the new GM2000HPS. The mounts look very similar and they function identically. Both mounts use the same computer that attaches to the mount with a single cable. The 1000 has a greater latitude range than the 2000. The 1000 slews at up to 15 degrees/sec whereas the 2000 slews at up to 20 degrees/sec. The 2000 uses the larger Centaurus tripod and the 1000 the smaller Aries tripod (but they are nearly identical except for size) and some of the accessories for the mounts are a little different, but that is about it.


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Tonk
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Re: Do direct drive mounts really not require guiding? new [Re: EFT]
      #6508408 - 05/05/14 06:35 PM

Quote:

Money is obviously not in question because top class mounts are very expensive so if someone can buy ASA or 10micron I presume one can also buy mono camera and good battery if shooting mobile.




Wooo what a presumption. Its taken me 10 years to save up for a top class mount and I don't yet have the dosh to get that nice mono. That's some years off still.

The thing is its the quality of the mount that is crucial to astrophotography so that's were I put my money. You can have the best camera in the world but it ain't going to deliver if your mount is the weak link.


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orion69
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Re: Do direct drive mounts really not require guiding? new [Re: Tonk]
      #6508509 - 05/05/14 07:42 PM

Sorry if I offended you, you are right, that did not sounded nice.
Actually, I'm in pretty much similar situation just taken slightly different path.


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: Tonk]
      #6508634 - 05/05/14 08:39 PM

Quote:

The thing is its the quality of the mount that is crucial to astrophotography so that's were I put my money. You can have the best camera in the world but it ain't going to deliver if your mount is the weak link.




Apparently this is no longer true. (quoted from ccd-newastro yahoo group). With 125ms sub-exposures it doesn't matter how *BLEEP* your mount is.


Celestron 8" f/10 EdgeHD

Photometrics 1k EMCCD

sub-exp time = 125ms (8 FPS)

http://www.stanmooreastro.com/images/M51_C8_39856x125ms.JPG
http://www.stanmooreastro.com/images/ngc3628_C8_22656x125ms.JPG


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psandelle
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6508700 - 05/05/14 09:17 PM

Orly - handheld is back!!!

Paul


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Ray Gralak
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Re: Do direct drive mounts really not require guiding? new [Re: frolinmod]
      #6509635 - 05/06/14 10:13 AM

Quote:

Quote:

Sure that can be done. Here's a few with a 20 inch scope done by Wolfgang Promper



I'll bet that 20 inch scope is far more rigid than an EdgeHD 14, which was mentioned in the post you replied to. The EdgeHD 14 flops around like a pancake. With that particular OTA an off-axis guider is needed for images over 5 minutes or so even with well modeled a world class mount. It's not the mount in this case, it's the OTA.



Actually, didn't the first part of the quote I responded to challenge unguided imaging with "large aperture"? I think 20-inches qualifies as large aperture.

And there are ways to make even a large aperture SCT work well unguided. You just need to know how to do it.

-Ray


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frolinmod
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Re: Do direct drive mounts really not require guiding? new [Re: Ray Gralak]
      #6511153 - 05/07/14 12:49 AM

Quote:

And there are ways to make even a large aperture SCT work well unguided. You just need to know how to do it.




Yeah, throw money at it until it becomes a CDK.


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EFT
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Re: Do direct drive mounts really not require guiding? new [Re: frolinmod]
      #6513249 - 05/08/14 01:42 AM

They finally posted Per's review of the GM2000HPS here: http://www.cloudynights.com/item.php?item_id=2969.

Edited by Dave M (05/08/14 04:25 PM)


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Per Frejvall
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Re: Do direct drive mounts really not require guiding? new [Re: EFT]
      #6513337 - 05/08/14 05:16 AM

Once they responded the tone of voice was very nice and pleasant, and the process quick. I just think there was a lot to take care of with the site changes and all.

/per


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james7ca
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6515181 - 05/09/14 02:53 AM

Quote:

Quote:

The thing is its the quality of the mount that is crucial to astrophotography so that's were I put my money. You can have the best camera in the world but it ain't going to deliver if your mount is the weak link.




Apparently this is no longer true. (quoted from ccd-newastro yahoo group). With 125ms sub-exposures it doesn't matter how *BLEEP* your mount is...



This is probably correct because eventually we MAY have sensors that actually count photons rather than the digital-analog hybrid sensors we have today. If you know precisely when and where a photon arrives on your sensor it shouldn't be that difficult to gather that data and track the image electronically. Thus, as long as the majority of the image remains on the sensor and you have a few stars that are bright enough to give a regular heart beat (a few photons every second?) then you probably won't need a mount that can precisely track the target. Conceptually, it would be like taking a series of very short exposures and then using software to align the stars (just as we can do today with stacking). However, with a totally digital sensor that could log individual photon arrival we should be able to do the alignment in realtime or just collect the time-stamped data and perform the alignment at a later time.

This probably won't happen within the next five years, it might be possible in ten years, but I'd be somewhat surprised if it doesn't happen in the next twenty years. Thus, our astrophotography using children or grandchildren may look back at our current times and almost laugh at all of the problems we had with the tracking of our subjects.


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Per Frejvall
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Reged: 09/28/12

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Re: Do direct drive mounts really not require guiding? new [Re: james7ca]
      #6515262 - 05/09/14 06:36 AM

Correct me if I am wrong, but ONE photons rips ONE electron into the well. With a well-depth of about 25,000 (KAF-8300) you can still expose for 20 minutes in order to reach the faint stuff. This, in turn, means that in 20 minutes you get about 12,500 photons representing half saturation. That's 10 and a half photons per second. Regardless of the sensor sensitivity we will get one photon in 125 ms.

So, does a normal sensor "miss" photons? Or is it a fact that there are only 10 of them hitting each pixel every second?

Confused...

/per


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TxStars
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Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #6516597 - 05/09/14 07:59 PM

There is already a way to image without tracking an object.
Look up "drift scan imaging" which is supported in some current imaging software.


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Footbag
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6516651 - 05/09/14 08:24 PM

Quote:

Quote:

The thing is its the quality of the mount that is crucial to astrophotography so that's were I put my money. You can have the best camera in the world but it ain't going to deliver if your mount is the weak link.




Apparently this is no longer true. (quoted from ccd-newastro yahoo group). With 125ms sub-exposures it doesn't matter how *BLEEP* your mount is.


Celestron 8" f/10 EdgeHD

Photometrics 1k EMCCD

sub-exp time = 125ms (8 FPS)

http://www.stanmooreastro.com/images/M51_C8_39856x125ms.JPG
http://www.stanmooreastro.com/images/ngc3628_C8_22656x125ms.JPG




Those are great results for unguided lucky imaging, but I'm going to assume it was taken with impressive equipment. If they were to put a $400 DSLR on it and expose for the same amount of time, even using short exposures, they may get similar results. Hard to say without the details. I think he uses a 14" RC. Some other images were close to an hour of recording and all in mono.

Also the pixels on the camera are 8 micron. I'll assume it has very low noise, but I don't know much about it. My guess is it's pricy.

Going unguided doesn't have to be cheaper, though. Just easier.


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: Footbag]
      #6517024 - 05/10/14 12:31 AM

He used a C8 EDGE. But the Photometrics EMCCD (electron-multiplying CCD) is $10k. Used. I have no idea what the new price is. $50K maybe.

Thing about these EMCCD's is that their "effective" QE is very high (one photon produces a lot of electrons, kind of like the Gen III NVG photomultiplier tubes, but using a CCD).


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Per Frejvall
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6517073 - 05/10/14 01:29 AM

So where is the resolution if one photon busts more electrons into the well? It's like multiplying an 8-bit analog to digital converter by 256 to get 16 bits of "dynamic range". You get it, but it comes in steps of 256 and hence does not have higher resolution...

Still missing something? Or are our present day CCDs "missing" photons that can be captured with EMCCDs?

/per


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Per Frejvall
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Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #6517078 - 05/10/14 01:39 AM

I read up on it... EMCCDs give much lower read noise, so they don't suffer from low electron counts in the well drowning in read noise. Gotcha In the end that leads to better S/N ratio, and our standard CCDs don't actually miss photons, rather suffer from the low counts disappearing in the noise.

All the best,

Per

/per


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freestar8n
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Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #6517238 - 05/10/14 07:26 AM

This is an old meandering thread, but does anyone know if the OP ever made a choice?

My own interest is a mount in the $10k range with 50 lb capacity. The main contenders would be ap1100 and paramount mx - both without encoders, vs. 10micron and asa, both with encoders, and only asa being direct drive.

My main interest is in autoguided imaging with a semi-permanent setup under telegizmos cover. This means that time to set up and polar align does matter, but I would also want fast startup from a previous setup - via hibernate or equivalent.

Another requirement is through the mount wiring. Also the communication protocol with the mount should be documented so I can control it with my own code.

I would like encoders if they work well and are very robust - but rather than viewing them as something that simplifies imaging - I would be concerned they would be a critical item that might break and require return to Europe for repair.

In that sense I can appreciate Korborh's description of the simplicity of AP and the ability to use it without computer. I used to be more of a fan of TheSky but I am not as crazy about TheSkyXPro.

It seems like this is just a transition time in mounts, with more encoders being included at lower price - and at the same time I think mounts that require pc's are evolving to work standalone with handcontrols as an option.

I would certainly want to see examples of guided and unguided images in long exposures. It would also help to see video of someone actually setting these things up for a) first time mobile setup and b) next night session - recovering from a hibernated setup.

Anyway - it's an interesting time.

Frank


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6517254 - 05/10/14 07:40 AM

Recovery from a hibernated setup with an AP mount is simplicity itself.

1) Pull the plug on the mount to hibernate - you don't explicitly need to park, the park positions are just useful for loading up

2) Power on the mount, select "Resume from park" and... you're off.

Can't get any simpler than that (incidentally.. the AP mounts don't have a power switch)

Incidentally.. for the first-time setup I am indebted to Rich (Starhawk) for this procedure (I have paraphrased it somewhat for more clarity):

Quote:


Load it up at park 3 - which is pointing north (declination 90, and counterweight down)

Have the mount DRIVE ITSELF to Park 1.

Open the clutches and level the OTA and mount arm with a torpedo level i.e. at Park 1, the OTA and counterweight shaft must both be horizontal.

GOTO to a star near the zenith.

Adjust the altitude and RA buttons to center it.

GOTO to a star near the horizon.

Adjust the azimuth and RA buttons to center it.





Now this isn't really necessary if you can see Polaris and have the RAPAS (or even the PASILL, I just got a PASILL and after carefully centering the reticle I believe I can get under 5' from the pole).

The above procedure is actually conceptually identical to the iOptron polar align routine. Once this has been done it is possible to guide all night. But if you want to do long unguided you'd still need to drift align.

I do not believe that the various ASPA routines (e.g. Celestron) are really any better than the above, due to uncertainty in centering the stars in the reticle.

The 10Micron routine in conjunction with plate-solving, however, is I believe much more accurate, but it requires the PC. If not plate-solving (i.e. just centering the reticle) I suspect the 10Micron PA procedure is no better than say Celestron ASPA, until you've put in a good number of stars in the model (say >5 or 6).


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Per Frejvall
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6518629 - 05/11/14 01:20 AM

I can only answer from a 10u view. Second session you just power it on. Nothing to select from the hand controller, nothing to do.

First session is just rough polar alignment followed by three stars, adjust mechanical screws as per the hand controller, then three or more stars. After that it is unguided galore!

/p


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Alph
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Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #6518704 - 05/11/14 03:22 AM

Quote:

I can only answer from a 10u view. Second session you just power it on. Nothing to select from the hand controller, nothing to do.

First session is just rough polar alignment followed by three stars, adjust mechanical screws as per the hand controller, then three or more stars. After that it is unguided galore!

/p






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Per Frejvall
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Re: Do direct drive mounts really not require guiding? new [Re: Alph]
      #6519319 - 05/11/14 01:11 PM

I don't understand that. Please elaborate...

/p


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Footbag
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6521013 - 05/12/14 12:54 PM

Quote:

Recovery from a hibernated setup with an AP mount is simplicity itself.

1) Pull the plug on the mount to hibernate - you don't explicitly need to park, the park positions are just useful for loading up

2) Power on the mount, select "Resume from park" and... you're off.

Can't get any simpler than that (incidentally.. the AP mounts don't have a power switch)






If you use auto-start, you don't even have to hit resume from park.


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timmbottoni
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Re: Do direct drive mounts really not require guiding? new [Re: Footbag]
      #6522044 - 05/12/14 10:22 PM

Watching this just amazes me - https://www.youtube.com/watch?v=XpQgCA5vcJk Anyone else see this?

Timm


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freestar8n
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Re: Do direct drive mounts really not require guiding? new [Re: timmbottoni]
      #6522290 - 05/13/14 03:39 AM

Thanks for the replies on polar alignment and restart - and the videos are nice to see. I didn't hear about the paramount mx, but it sounds like the others do recover from hibernate promptly. I guess the paramount has to do some sort of startup routine - but I'm not sure.

I occasionally get urges to switch to high end system - but I am more inclined to wait until things settle out. Here are some things that bother me:

There is a lot of nickel and diming in accessories needed to make a complete system. I would need a tripod/portable pier for a driveway setup - and that is a full $2k for the mx. It is cheaper for AP, but then the counterweights aren't included in some systems. You can get a separate tripod, but then you need a pier adapter that also isn't cheap. None of this stuff costs a lot - but it does add up to go well over $10k.

Paramount is annoying because I already have TheSkyXPro, but I don't have the camera software or tpoint. I could get them for my current mount - but I wouldn't get a refund if I got the mx. That is 330+200+250 = $780 worth of software right there - and from what I can see the camera add on isn't sophisticated enough for imaging and would only be good for tpoint.

The AP hand control is nice and seems bullet proof, but it looks like it only does a 2-star alignment with no cone or dec. offset term. The mount may be nearly perfect - but if the optic axis isn't perfectly aligned, the 2-star alignment would be affected. I'm not sure how much this would affect goto accuracy and it may be ok - but having a system with perhaps 5 alignment stars would help a lot. 10micron appears to be the only one with a handcontrol that can start up from hibernate and use an accurate model.

Some people have asked about satellite tracking, and that is where any periodic error in ra or dec. will really show. Which mounts can model the periodic error in both RA and Dec, so that high speed satellite tracking will have it dynamically corrected? Encoders won't automatically solve this stuff but they should help - and ultimately I would want to know how accurately a fast satellite like the ISS can be tracked - i.e. how much it will wiggle around the path.

There are other things that are hard to know - like how robust they are over 3 years of exposure including occasional rain soakings. In my case it has a good chance to happen - so how resilient are these things? How does moisture and dust accumulate in the encoders over time? It's nice to know you can replace the MX boards - but at about $800.

Frank


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6522303 - 05/13/14 04:20 AM

Frank the AP hand control only does one star alignments.

But the mount is very orthogonal. There's more error from flexure in my newtonian tube.

What I do (visually) is slew to a bright star, center it and RCAL, then slew to the DSO close by. If I have a computer I just slew to the DSO, plate-solve, RCAL, then reslew. My pointing errors are around 1 degree (to 2 degrees after a meridian flip) but I suspect my polar alignment is quite off because there is visible trailing even in 1 minute exposures at 400mm.

AP pointing accuracy is directly dependent on how good the polar alignment is.

I heard that the AP hand control can survive submersion. There is that..

I'm writing software to do automated pointing/plate-solving and dual-axis custom tracking on my AP mount. I had a minor breakthrough last night I think I can throw away my guide scope now.

My eventual goal is to port all the software to a Raspberry Pi with a PiFace Control, then I will be able to do all my routines via an IR remote control. And the RasPi consumes tiny amounts of power.

For your use case I would suggest find a used AP900 or 1200. They are under 7K now and usually come with accessories so you don't get nickel and dimed to death. I am not convinced about the utility of encoders given that these mounts have sub-arcsecond residual PE.

This is the native PE of my Mach1. After PEM it is sub-arcsecond (about 0.9").



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freestar8n
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Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6522321 - 05/13/14 04:46 AM

Thanks - I was going by the AP handcontrol manual that referred to "two star calibration" but I see that is a form of polar alignment that involves mount adjustments - and not a mount model.

A lot of things about AP are changing so it's hard for me to keep track. But yes I guess the hc only effectively does a one-star alignment, and it assumes the mount is perfect and there is no cone/dec. offset.

Thanks for the update on your controller - it sounds like the AP communication interface is well documented and there is no proprietary stuff - which is also good.

Some things I would absolutely want - including through the mount wiring. I'm not sure which ones have it - but in this range I would be looking at the ap-1100.

Frank


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6522324 - 05/13/14 04:50 AM

The Mach1, 1100, and 1600 all have through-the-mount wiring. Considering that the 1100 is $8800 it probably is the best bet. The problem is you'll get nickel-and-dimed on the accessories.

I would just get the flat-surface adapter, and a saddle (or buy a saddle from ADM Accessories). The weights.. you can go for AP's weights, or get Losmandy weights. They'd need to be bored out to 1.875". I would use a third-party tripod, a Meade heavy-duty field tripod (the monstrous one), a Losmandy HD tripod, or CGE Pro tripod would work fine. Or if you have a permanent pier so much the better.

I ended up with a Berlebach Planet but it's a little too small for a 900 or 1100.


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WadeH237
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Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6522767 - 05/13/14 11:35 AM

Quote:

There are other things that are hard to know - like how robust they are over 3 years of exposure including occasional rain soakings. In my case it has a good chance to happen - so how resilient are these things?




There are a number of Astro-Physics mounts set up and exposed to the elements full time near the south pole in Antarctica. I believe that the only modification that they make is that the run them without grease due to the extreme cold.

I have my setup outside year round with a Telegizmos 365 cover here in the damp Pacific Northwest. I worry a bit about the camera and scope (and need to run a gun safe dehumidifier under the cover to keep the optics from dewing on the inside). I also see some surface rust on the screw heads of some of the cheaper equipment.

I don't worry at all about the mount, though. Before committing to leaving it outside in this environment, I spoke with Astro-Physics and they assured me that there would be no concerns. And after nearly a year set up like this, I can't find any signs of wear on the mount. Once I clean off spider webs, etc., the mount looks just like new.


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freestar8n
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Re: Do direct drive mounts really not require guiding? new [Re: WadeH237]
      #6522845 - 05/13/14 12:13 PM

Yes - I'm pretty sold on AP being reliable and robust. I think it wins in that department compared to the other three I mentioned. Paramount has more elaborate electronics and no encoders, while 10micron and asa do have encoders, and I'm a little concerned about added complexity and possible reliability issues in driveway conditions.

Frank


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Peter in Reno
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Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6522922 - 05/13/14 12:47 PM

Hi Frank,

Don't forget RAPAS (Right Angle Polar Alignment Scope) for AP mounts. It's darn accurate and quick. All you have to do is do an initial precise polar alignment like drift alignment, PEMPro or whatever you prefer and then make tiny adjustments to RAPAS to match the software application which shows exactly where Polaris should currently be. From then on, all you have to do is level the pier/tripod and it takes a few minutes to polar align with RAPAS. One of your mount requirement is quick polar alignment. The only drawback is it costs a whopping $390 but worth it if your setup is always portable.

Like others said, AP pointing is pretty accurate if polar alignment is good. Just slew to a known star near your target DSO, RCAL (similar to sync), then slew to target DSO and you are ready for imaging. Pointing from then on should be accurate at same side of Meridian if your scope is not well orthogonal with the mount. To slew to new target at other side of Meridian, just slew to known star at other side of Meridian and RCAL, simple. All of them can be done with hand controller or PC.

I would study AP mounts very closely to make sure this is the mount you are looking for. A-P web site has lots of documentation available including software commands to control A-P electronic box (GTOCP3). A-P GTO Yahoo Groups is a great place to start.

You can see pictures of my current setup in my signature (Peter's Gallery). Right now they are for visual setup. I am back from imaging hiatus and will post new pictures of my setup with imaging equipment later.

Good luck with your mount decision.

Peter

Edited by Peter in Reno (05/13/14 01:01 PM)


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korborh
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Re: Do direct drive mounts really not require guiding? new [Re: Peter in Reno]
      #6523020 - 05/13/14 01:33 PM

Hi Frank,

I think the AP mount is overall more robust than the MX. This is based on user experiences and reports of issues. I think the MX worm-block is much more complex and more prone to issues. You can sign-up (if not already) to SB forums and read about the user experiences.

I have used Paramount ME but not the MX. Both AP and Paramount are at the top in mechanical precision and quality. Both companies have excellent customer support.

But I think AP wins in robustness, simplicity and portability. Paramount wins for unattended permanent installation and for survey type of automated work where night over night repeatable multi-object pointing is desired. The homing switches in Paramount make this very convenient.

I don't like about the AP is that it has no pointing model...even something that would correct for pointing after meridian flip. So even for visual, not having a basic pointing model is annoying. After meridian flip, I cannot plate solve and have to Re-sync using my e-finder. Also for Polar alignment, I'd definitely consider the RAPAS. A friend has it and its all he needs for polar aligning for imaging.

The AP has clutches and Paramount does not. I like clutches and I think it makes the mount more robust and easy to use - eg. protection from accidental bumps.

The AP can be controlled with many applications. But for Paramount, one is tied to the CPU-intensive SkyX.

With the Paramount, the software/mount is in control and one has to follow its rules. With AP, if you know what you are doing, you can do things like track something all night without meridian flip, by starting the scope down and weights up. I use this feature for exoplanet transit work where meridian flips are not desirable.

The nickel-diming is more on the SB side I think. Their accessories (batteries, tripod etc.) are more overpriced and the software too. Like the camera add-on alone costs $200 ...and its just an add-on. This is the same price is awesome software packages like Skytools Pro and PixInsight.

For me, bottom line is for portable/semi-perm installation, AP wins out. If I had a remote permanent setup or If my main work was survey/supernova-hunting etc., I'd definitely go with a Paramount.


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timmbottoni
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Re: Do direct drive mounts really not require guiding? new [Re: korborh]
      #6523048 - 05/13/14 01:43 PM

This is a fascinating discussion, but what seems odd to me is that it has evolved away from "direct drive" almost entirely.

Does anyone have any comments or comparisons to any of these direct-drive mounts?

http://www.skyvision.fr/wordpress/mount/direct-drive-mount/?lang=en

http://planewave.com/technology/mechanical-design/

http://www.astrosysteme.at/eng/mounts.html

Thanks,

Timm


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freestar8n
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Re: Do direct drive mounts really not require guiding? new [Re: korborh]
      #6523102 - 05/13/14 02:14 PM

Thanks for the info Peter and Korborh. Yes, the right angle polar scope seems worth it and should work well - but to take it to the next level of accuracy I would need a computer and mount modeling software - so that makes it more like the paramount. I think I would like paramount more if I were happier with TheSkyXPro, but I haven't been. It uses a lot of cpu and I'm not crazy about the UI changes.

Frank


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Footbag
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Re: Do direct drive mounts really not require guiding? new [Re: timmbottoni]
      #6523106 - 05/13/14 02:16 PM

I love the AP hand control. I was actually worried that I'd miss the old Celestron one. The AP has much more information and does seem bulletproof.

Of course, I was doing a solar animation on Sunday, and I looked down at the HC. It was blank. I panicked, and stopped my solar run. Restarted the mount, and the HC came back. I'm pretty sure it overheated. It was pretty hot and I left it sitting there facing up.


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freestar8n
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Re: Do direct drive mounts really not require guiding? new [Re: timmbottoni]
      #6523120 - 05/13/14 02:24 PM

I guess the OP hasn't been around lately - but I took the original question really to refer to high res encoders and not direct drive per se. It's the encoders and a good mount model that lessen the need for guiding and not direct drive.

If you look at direct drive mounts with encoders in the $10k range - the one I know of is ASA. Are there others? PlaneWave looks great but they list it at $23.5k.

And I have my own answer to the subject question - and that is *no* if you have good seeing and long focal length and are going for highest res in long exposures - and double no if you have an sct rather than a refractor or very high end ota.

Many people in this thread don't care at all if there is a loss of image quality because they are mainly interested in convenience rather than tighter stars. There is nothing wrong with that, but it makes it very easy to answer yes to the question - if you are willing to trade off imaging ease for small fwhm.

Frank


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Per Frejvall
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Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6523198 - 05/13/14 03:10 PM

Quote:

Yes - I'm pretty sold on AP being reliable and robust. I think it wins in that department compared to the other three I mentioned. Paramount has more elaborate electronics and no encoders, while 10micron and asa do have encoders, and I'm a little concerned about added complexity and possible reliability issues in driveway conditions.

Frank




There is absolutely no complexity in using a 10Micron mount. In fact, you do not even need a computer to do unguided imaging. There is virtually no PE as this is taken out by the encoders - which are IN the main motor control loop. In short, it is not a bolt-on solution; instead, everything is integrated into the mounts. I again refer to Tonk when it comes to portable imaging without a computer - unguided. As for reliability... One cable from the mount to the control box. Handset connected to control box. GO. No encoder cables, no calibration, no homing, no getting lost.

/per


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Peter in Reno
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Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #6523214 - 05/13/14 03:19 PM

Frank,

10Micron web site has a forum. I suggest you to join their forum about 10Micron mount discussions. Just sign up and read the threads.

Peter


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freestar8n
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Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #6523221 - 05/13/14 03:23 PM

I'm not referring to complexity in using the mount - I'm talking about mechanical/electronic complexity and robustness in a driveway environment. Overall 10micron wins for me in terms of having an hc with a mount model - and it looks like all four will start up quickly from a hibernate. But when it comes to encoders, they definitely add complexity to the system, and they become something that can break.

Does 10micron have a failsafe mode that lets the mount still work if an encoder malfunctions? They may be fine outside for many years - but that is one thing I would be concerned about.

I'm also concerned about fixing things myself - which is no problem if the systems are fairly simple, but might be harder with encoders.

Frank


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timmbottoni
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Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6523846 - 05/13/14 09:53 PM

I'm sure I wouldn't attempt to fix any mount in this price range myself. All said, I am strongly leaning towards 10 Micron (someday hopefully)

Timm


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austin.grant
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Re: Do direct drive mounts really not require guiding? new [Re: timmbottoni]
      #6523866 - 05/13/14 10:01 PM

Quote:

I'm sure I wouldn't attempt to fix any mount in this price range myself. All said, I am strongly leaning towards 10 Micron (someday hopefully)

Timm




I surely wouldn't expect to have to repair any mount in this price range!


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: austin.grant]
      #6523955 - 05/13/14 10:40 PM

Since the encoders are in the servo loop for 10micron, I seriously doubt they would work if the encoders failed. But I could be wrong... maybe there is a sanity check between the motor encoder ticks and the main encoder ticks, and if they're too far apart, believe the motor encoder.

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WadeH237
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Re: Do direct drive mounts really not require guiding? new [Re: austin.grant]
      #6524016 - 05/13/14 11:15 PM

Quote:

Quote:

I'm sure I wouldn't attempt to fix any mount in this price range myself. All said, I am strongly leaning towards 10 Micron (someday hopefully)

Timm




I surely wouldn't expect to have to repair any mount in this price range!




Interesting.

I consider user serviceability to be one of the really nice features in this price range.

For example, if my CGE were to develop a problem with excessive backlash, and I were to call Celestron, they would say to send it in for repair. If I were lucky, it only take a month or two to get it back. If I wanted to go ahead and fix the problem myself, I could do so, but I would be on my own. And getting the tension correct on a CGE is notoriously finicky.

For my AP1600, if I were to need the same procedure, AP would point me to the well documented process for setting the gear tension. It would take less than 2 minutes per axis and I'd have the problem solved.

Telescope mounts are scientific instruments. They require some periodic maintenance, and the owner benefits from a solid understanding of how they work. My experience with the lower cost mounts is that the manufacturers don't want you getting anywhere near them with a screwdriver. My experience at the high end is that the manufacturers are happy to explain to you how to service them yourselves...but if you really aren't comfortable, they'll let you send them back for service.

Oh, and another big difference is that, with the lower end stuff, you'll be sending back the entire mount if you need service. With the higher end - at least with AP - if you get into a situation where you need to send it back, you will probably be able to send back just the part that needs to be serviced, and not the whole mount.


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austin.grant
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Re: Do direct drive mounts really not require guiding? new [Re: WadeH237]
      #6524060 - 05/13/14 11:47 PM

Wade,

I agree totally with your synopsis that the higher-end gear is ultimately more user-friendly when it comes to service. That said, besides capacity and precision, I'm paying for reliability. I find that my CGE is easy to work on, and parts are readily available. That said, I expect when I move up to a better class of mount I won't to have to work on it. It's not worth the $7K plus investment to play the same games of repeatedly tweaking gear mesh, checking tolerances, etc...


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EFT
Vendor - Deep Space Products
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Re: Do direct drive mounts really not require guiding? new [Re: austin.grant]
      #6524133 - 05/14/14 12:42 AM

Quote:

Quote:

I'm sure I wouldn't attempt to fix any mount in this price range myself. All said, I am strongly leaning towards 10 Micron (someday hopefully)

Timm




I surely wouldn't expect to have to repair any mount in this price range!




I don't think that anyone expects to have to repair premium mounts in general, but *BLEEP* happens. Electrical surges from storms, water damage from a leaking observatory or flooding and any number of unpredictable things can happen beside the rare occasion of a faulty board component that goes bad for one reason or another. But unlike a $1500 mount, you don't want to go tearing into a high precision mount with absolute encoders except where directed to by the manufacturer. Boards and controllers may be readily accessible an easily changed, but the encoders are generally not something to mess with. Chances are much higher that you may make things worse rather than better. Applying the term "precision" to the average mass-produced mount seems a bit silly when you see what it means in regard to a premium mount.


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EFT
Vendor - Deep Space Products
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Re: Do direct drive mounts really not require guiding? new [Re: austin.grant]
      #6524156 - 05/14/14 01:04 AM

Quote:

Wade,

I agree totally with your synopsis that the higher-end gear is ultimately more user-friendly when it comes to service. That said, besides capacity and precision, I'm paying for reliability. I find that my CGE is easy to work on, and parts are readily available. That said, I expect when I move up to a better class of mount I won't to have to work on it. It's not worth the $7K plus investment to play the same games of repeatedly tweaking gear mesh, checking tolerances, etc...




I think that it is far more important that the premium mount very rarely, if ever require adjustment.

Edited by Dave M (05/14/14 03:49 PM)


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Per Frejvall
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Re: Do direct drive mounts really not require guiding? new [Re: EFT]
      #6524186 - 05/14/14 01:52 AM

I disagree about user serviceability in the upper range. There is no adjustment needed on the gears of the 10Micron mounts and letting a user adjust an encoder mounting - with extreme precision - does not sound viable to me.

My GM2000HPS is now two years old and is still tight as a single piece of metal. No slack at all and runs perfectly. The manual maintenance section (1/4 of a page) ends with "No checks or periodical corrections are needed."

/per


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EFT
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Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6524213 - 05/14/14 02:31 AM

Quote:

I'm not referring to complexity in using the mount - I'm talking about mechanical/electronic complexity and robustness in a driveway environment. Overall 10micron wins for me in terms of having an hc with a mount model - and it looks like all four will start up quickly from a hibernate. But when it comes to encoders, they definitely add complexity to the system, and they become something that can break.

Does 10micron have a failsafe mode that lets the mount still work if an encoder malfunctions? They may be fine outside for many years - but that is one thing I would be concerned about.

Frank




None of the premium mounts being discussed are wall flowers. The smaller versions are designed for portable field use a lot tougher than pulling them out into the driveway on a scope roller. The large mounts are designed for permanent mounting and heavy use with very large equipment.

Encoders are not the most complex thing in the world. Much of the complexity actually comes in the firmware and software needed to collect and interpret the data that they provide and then apply it to the system. As far as adding actual complexity to the mount, not so much. But they are high precision instruments that should not simply be fiddled with.

As far as a "failsafe" mode that would allow and absolute encoder mount like the 10Micron to continue to work without the encoders, that is fairly absurd. Why would you even want such a thing? In the unlikely event there was a failure of some kind I would think that the preference would be to get it fixed ASAP, not continue playing with a broken piece of expensive equipment. Where bolt-on encoder solutions are concerned, I would expect that you could continue to use the mount if the absolute encoders failed, but you would also loose all the benefit that the encoders bring to the game and likely not be prepared to or want to go back to using the mount without the encoders. It is highly unlikely that any of the mounts with absolute encoders integrated into the mount would be able to function with out them because the entire software and firmware system is designed around them and there is little reason that a manufacturer would want to design a system in such a way that they could be operated without them. The exception may be in some of the attempts being made by some of the mass-production manufactures to integrate this kind of technology on the cheap. So far the results are not all that promising and the ability to be able to work on the mount yourself may be desirable just like with the other mass-produced mounts.

I don't know about all of the premium mounts, but in most cases you are not talking about having to ship the mount overseas to be gone for months just to get it fixed. It makes little sense in the US market for that to be the case. It is easy to push all possible failures and contingencies to the extreme, but after a while it doesn't make sense to do so and it only increases the price of equipment even more by have to incorporate to separate drive and read systems into the mounts. One of the reasons that you are paying so much for these premium mounts is that they are built with the expectation that problems, particularly hardware problems will be minimal. Most issues will arise in firmware and software that can be changed and easily redistributed in most cases.


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freestar8n
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Re: Do direct drive mounts really not require guiding? new [Re: EFT]
      #6524235 - 05/14/14 03:02 AM

There are two reasons I am concerned about downsides of encoders. First, my use case would be different from many others in that the scope would be outside under a telegizmos 365 cover and not in an observatory. This would expose it more to the elements - particularly dust and moisture - that might affect the encoders. I don't know if these mounts have been in use in such environments long enough to assess how well they would do.

The other reason is anecdotal. I know someone who has an expensive mount in a remote observatory, and something about the encoders failed and caused the mount to be completely unusable. Not only did he lose observing time, but he had to make a visit to the remote observatory to investigate the problem. I am not sure how the story ended - but that gave me concerns. He was actively involved in investigating the problem and trying to resolve it himself, and did not simply say, "It's busted so I'll send it back to be fixed by the pros." I don't think he dissected the mount, but he did basic cleaning and checking of dust entry points.

He could not continue "playing" with it. The encoders are a critical link in the chain, and a speck of dust in the wrong place could brick the entire mount. In a remote observatory application, a form of redundancy in critical components seems like an important thing.

Do any mounts with encoders have a failsafe mode that lets them continue to operate, at lower res., if an encoder fails?

So - is it absurd to think the mount should have a failsafe mode? I don't think so - and it could be done by having normal low-res encoders on the motor itself before the gear train. That is not an option for the ASA since it is direct drive - so I guess that is a real problem - but for 10micron or others, encoders on the motor itself make sense - assuming they aren't there already.

I also don't think it's absurd to fix things yourself as long as the procedures are outlined and no expensive and specialized tools are required. That may well not be an option for a mount with encoders and they really may need to be shipped somewhere - but that would make them less attractive for long term ownership by people who are hands-on with their equipment.

I would like encoders and I would like direct drive - but I do think the technologies are fairly new and evolving, and they haven't accumulated the track record of AP's and Paramounts without encoders.

Frank


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orlyandico
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Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6524242 - 05/14/14 03:13 AM

I'm sure the AP's will continue working without the encoders, because AP's solution is a bolt-on extra box that talks to the GTO control box via the 2nd serial port. So if your encoders died, take off the encoder control box and you have a bog-standard encoder-less AP mount.

That said companies like Heidenhain make IP65 rated encoders, which would be even more weatherproof than the mounts themselves. AP's Renishaw Resolutes have an IP64 rating (dust-tight, and protected from splashing water of duration 5 minutes, water volume 10 litres per minute at 80Ė100 kPa).


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Tonk
Postmaster
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Reged: 08/19/04

Loc: Leeds, UK, 54N
Re: Do direct drive mounts really not require guiding? new [Re: orlyandico]
      #6524382 - 05/14/14 07:45 AM

Quote:

First, my use case would be different from many others in that the scope would be outside under a telegizmos 365 cover and not in an observatory. This would expose it more to the elements - particularly dust and moisture - that might affect the encoders. I don't know if these mounts have been in use in such environments long enough to assess how well they would do.





I'll let you know when my 10Micron GM1000HPS fails. Except for 8 weeks in Jan/Feb its been outside under a Telegizmo cover since last August. Here in the UK it rains more that it shines so air humidity is always high. The good news is it still works - there no rust - the counter weight is still shiny and I still haven't dropped a 10 minute unguided shot.

I would be seriously interested in how you could break an encoder on this mount other than dropping the whole thing onto concrete. What sort of failure mode would folks expect to happen otherwise? I guess the one risk is forgetting to release the clutches when transporting. I'm very very aware of this as I do drag the beast around on frequent occasions. This is less likely a "forgetting" issue for a permanent setup.

The encoders are totally sealed inside and there is no user access. The bolts are covered with "warranty voided if broken" stickers. I think the only thing you need to open is the 4 small bolts to change the button cell battery, everything else is "closed".

To add to Per's comments about maintenance I seem to recall there is an option for 10 year routine tuning service if you so wish.


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Per Frejvall
sage


Reged: 09/28/12

Loc: Saltsjöbaden, Sweden
Re: Do direct drive mounts really not require guiding? new [Re: Tonk]
      #6524487 - 05/14/14 09:05 AM

Right, Tonk, the encoders are in there, enclosed and not exposed to the elements. The motor encoders are in the motors, and the motors are inside of the mount. Same thing with those - not accessible, not exposed.

My GM2000HPS has been indoors very little over two the years that I have had it. It has spent most of its time under a standard barbeque grill cover on th ebalcony, and now spends its days in the Provence observatory with just a roof, no insulation and no seals. In fact, there isn't even a door...

So, basically a mount fails or it doesn't. I, for one, am perfectly comfortable with tearing my NEQ6 to pieces but I do not want to tinker with my 10Micron mounts. An analogy is my boat and my car. I am perfectly comfortable with ripping the GM engines apart in the boat, but my high-tech W12 engine in the car is not to be tinkered with

/per


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6524590 - 05/14/14 10:06 AM

Quote:

There are two reasons I am concerned about downsides of encoders. First, my use case would be different from many others in that the scope would be outside under a telegizmos 365 cover and not in an observatory. This would expose it more to the elements - particularly dust and moisture - that might affect the encoders. I don't know if these mounts have been in use in such environments long enough to assess how well they would do.

The other reason is anecdotal. I know someone who has an expensive mount in a remote observatory, and something about the encoders failed and caused the mount to be completely unusable. Not only did he lose observing time, but he had to make a visit to the remote observatory to investigate the problem. I am not sure how the story ended - but that gave me concerns. He was actively involved in investigating the problem and trying to resolve it himself, and did not simply say, "It's busted so I'll send it back to be fixed by the pros." I don't think he dissected the mount, but he did basic cleaning and checking of dust entry points.

He could not continue "playing" with it. The encoders are a critical link in the chain, and a speck of dust in the wrong place could brick the entire mount. In a remote observatory application, a form of redundancy in critical components seems like an important thing.

Do any mounts with encoders have a failsafe mode that lets them continue to operate, at lower res., if an encoder fails?

So - is it absurd to think the mount should have a failsafe mode? I don't think so - and it could be done by having normal low-res encoders on the motor itself before the gear train. That is not an option for the ASA since it is direct drive - so I guess that is a real problem - but for 10micron or others, encoders on the motor itself make sense - assuming they aren't there already.

I also don't think it's absurd to fix things yourself as long as the procedures are outlined and no expensive and specialized tools are required. That may well not be an option for a mount with encoders and they really may need to be shipped somewhere - but that would make them less attractive for long term ownership by people who are hands-on with their equipment.

I would like encoders and I would like direct drive - but I do think the technologies are fairly new and evolving, and they haven't accumulated the track record of AP's and Paramounts without encoders.

Frank




Yes it is absurd. If someone spends $20K on a mount, there are some things that they may be able to trouble shoot with guidance (written or direct), but they should not be expected to or have to do this. If you want a well machined mount that you can tinker with to your heart's content, then you can spend a lot less for at least one mount that is out there. If you expect to or want to tinker with an expensive premium mount, then you are wasting your money. That's not what you should be paying for. You can bet that some specialized tools, either mechanical or electronic are necessary to work on much of this equipment at certain levels. There may be some day, well down the line, when the warranty is up and the value of the mount has significantly decreased when you might be inclined to fiddle with it and try to make your own repairs, but even those of us who are constant tinkerers are wise enough to realize that you don't mess around with your $100K sports car under the same circumstances unless you are a trained professional with experience on that particular car. If you like rebuilding classic VW Beetles, then don't by a Lamborghini.

As far as storing the 10Micron mount outside under a cover, Per and Tonk the people to ask about that since they have both done that extensively.

For a mount with absolute encoders incorporated into the mount, adding redundant backup low resolution encoders to operate the mount independently from the absolute encoders would be a sign of a lack of faith in the technology being used, and an extra and unnecessary expense that the vast majority of people would not need or want to pay for, and certainly additional complexity in the mount firmware and software. In fact, some, if not all, of the non-direct-drive mounts with absolute encoders do have more than one set of encoders because it is a closed loop system that has to be able to reference and check itself as it runs. But adding some ability for the mount to work well below its rated high precision is something that would be rarely, if ever, necessary and almost completely undesirable for the vast majority of owners who would need to pay for that additional functionality. Just look at AP right now and you will see that the additional functionality of absolute encoders is clearly not ending up being very desirable with their mounts. Yes, it gives people some more capabilities with the mount, but it is clearly not enough that most people want to pay for it. The same would be even more true for adding a lower precision capability to a mount with built-in absolute encoders.

If you are looking for someone to convince you that direct-drive and absolute encoder mounts are the way to go, you are not likely to find them since it seems fairly clear that you are pretty set against them at this point because of all of the possible contingencies that you can come up with for there to be problems with these mounts. Problems that you don't feel are an issue with the standard drive mounts. There are other means to get to similar, if not the same, performance ends and I would suggest you just select one of them and not agonize over the decision further unless you are truly undecided (but I don't thing you are).


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psandelle
professor emeritus


Reged: 06/18/08

Loc: Los Angeles
Re: Do direct drive mounts really not require guiding? new [Re: EFT]
      #6524714 - 05/14/14 11:11 AM

Really, it is like picking Ferrari (my choice of car in the past), Lamborghini, Porsche, a muscle car. At a certain point with the high end mounts, personal choices become involved.

Me, I like the idea of unguided. Now, AP (when their software comes out) says they don't need encoders for that, and that's cool, but it seems encoders make it much more efficient...so I'm going for that.

On the other hand, some prefer something a little more brute-force and familiar (AP without encoders). It's a technology that's been on the market for a long time. Cool.

Paramounts are kind of a combination of the two and have a long history of great remote observing in their favor.

10Micron is so cool. But, for me, they don't have an in-saddle usb and power hub (or through the mount wiring). That's a personal choice. So I'll try the ASA mounts (until something else comes along before I buy).

They're all GREAT! And they're all expensive. After a certain point it really is a personal choice of what you like or don't like. But I don't think encoders are that finicky from what I've seen and heard out there. Other things are...but not the encoders. Can they go wrong? Heck, I was set up next to a guy with a Mach 1 and his hand controller totally fritzed. No reason why, just went belly up. Do I think that happens a lot to AP hand controllers? Nope. But it did happen. I'm not going to hold it against hand controllers.

Anyway, don't think any of these mounts are a bad choice; it's what you feel comfortable with.

Ex-Ferrari guy,

Paul


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freestar8n
Post Laureate
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Reged: 10/12/07

Re: Do direct drive mounts really not require guiding? new [Re: EFT]
      #6524871 - 05/14/14 12:48 PM

Well as orlyandico mentioned, the ap1100 basically has the encoder system added on - so obviously it can work either way. I don't know if the two systems are fully decoupled, but there would be good reason to have them coexist and provide redundancy. They are also somewhat user-serviceable since they can be added on after purchase of an ap1100 - according to the web site.

APM describe their use of redundancy as a consistency check between what the motor sees and what the axis is doing - as an indication it hit some resistance.

I believe there is a similar redundancy in the Ascension mount that provides a consistency check between motor and axis encoders. The manual for the RH200 is refreshingly open about the encoder technology and explains that differential thermal expansion can cause a shift in the read head distance from the encoder, which could lead to errors. It is therefore user serviceable and described in the manual.

You are welcome to view these approaches as "absurd" - but what I am describing can be found in a wide range of systems including very high end. It's basic engineering practice not just to assume a fancy gizmo will work perfectly all the time and can be incorporated into an already complex system with no possible failure modes.

So I guess another thing to look for with encoders is whether they have a live indication of a discrepancy between the absolute encoders and the motor encoders. Obviously some do have this feature - and it seems like a good thing.

I'm not sure if anything like that is possible with direct drive mounts - but in that case the motor is more directly coupled to the encoders and the torque is directly sensed from the axis. The fact that asa mounts can measure balance is a cool feature.

Frank


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Per Frejvall
sage


Reged: 09/28/12

Loc: Saltsjöbaden, Sweden
Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6525002 - 05/14/14 01:44 PM

Frank,

The 10Micron firmware constantly checks the consistency between the servo loop (motor encoders) and the axis response (absolute encoders). In fact, that is the way the PE is virtually eliminated. The encoder technology used is not the same as the Planewave, Bisque or AP offerings and sport a patented solution for making an encoder read head distance independent. So, the encoders are there, and totally integrated into the solution, not a bolt-on, and they do not suffer from thermal things happening in the surrounding metal. They were developed specifically for mount use.

The firmware also includes a balancing measurement routine which is easy to use. You measure each axis separately and the hand-pad will tell you how much and in which direction error is. It will say things like "0.1% bottom heavy", "1.3% top heavy", "0.2% shaft heavy" or "1.1% scope heavy". When you do it the fifth time you wil lhave developed a feel for how much the scope needs to go up from a 0.% bottom heavy situation or how much to move the weights for a 0.5% shaft or scope heavy one.

We may differ in opinion about how user serviceable a mount should be, and I don't mind that. What I do feel is that most people (not specifically you) judge the 10Micron offerings from the standpoint of other manufacturers' offerings, and that is not the right approach. Most have an easier time judging the ASA stuff because the technology is so radically different. I have seen people that will not give up until they get a PE figure for comparison. No problem with ASA; they buy that it doesn't have it. More problematic with 10Micron; no PE (or virtually no PE) and it still has a worm solution for the main gear... Encoder technology

One last thing... Discrepancy between the motor and the shaft encoder is not an important factor. The motor encoder tells the feedback loop how to run the motor, and the shaft encoder augments the same control loop with net result inputs. Thus, if you were to measure the discrepancy - which by itself is difficult as one is absolute and one is not - you would find the inherent PE of the worm system. I find that cool

/per


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Footbag
Postmaster
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Reged: 04/13/09

Loc: Scranton, PA
Re: Do direct drive mounts really not require guiding? new [Re: freestar8n]
      #6525039 - 05/14/14 01:59 PM

Quote:



I'm not sure if anything like that is possible with direct drive mounts - but in that case the motor is more directly coupled to the encoders and the torque is directly sensed from the axis. The fact that asa mounts can measure balance is a cool feature.

Frank




I seem to remember Roland saying that you can measure the AP balance by using a voltage meter. Since I'm using auto-start, it's an interesting feature. No need to open the clutches and lose my sync.

I haven't tried it yet, but I'm planning on it.


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freestar8n
Post Laureate
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Reged: 10/12/07

Re: Do direct drive mounts really not require guiding? new [Re: Per Frejvall]
      #6525095 - 05/14/14 02:21 PM

Thanks - that's all good info. I view the main four mounts I'm talking about as having their own strong features so I don't see any clear ranking. I'm interested in learning more about the differences and I expect they will be evolving - so it's an interesting time, but there are clearly good options out there for a variety of needs.

And I assume they will all work pretty well in a driveway setting, but I guess I got spooked by one anecdote. It's good to know there are differences in the way the encoders are implemented - and some are intended to be serviceable while others are not. I agree that as long as it is completely sealed and it never fails - you won't have any need to service it - and that would be a good thing.

Frank


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WadeH237
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
Re: Do direct drive mounts really not require guiding? new [Re: EFT]
      #6525420 - 05/14/14 05:39 PM

Quote:

I think that it is far more important that the premium mount very rarely, if ever require adjustment.




Just to be clear, I am not suggesting in any way that you should expect a premium mount to require frequent maintenance.

I am suggesting that it may not be reasonable to expect that it will run forever without some kind of maintenance or work to address "stuff" that happens. And when it does, I expect that it'll be no big deal on a premium mount. For example, the backlash adjustment that I used as my earlier example isn't typically necessary just due to normal use. I've seen a number of cases where someone dropped their mount, or it suffered rough handling in shipping. Pretty much all the time, that gear mesh adjustment has been the only service required. And it's a two minute job that anyone can do.

I also disagree with the idea that just because you spend a lot of money on a mount, that you should not be expected to understand the equipment. Frankly, the more I spend, the less I expect it to be a black box. Yes, I do expect it to "just work". But I also want to be confident that, should something happen to it, getting it back to "just working" should be simple, and it should miss little or no time in service.

Finally, in case there is misunderstanding, I have no complaints about any of my Celestron mounts. I am happy enough with them that I've owned as many as 4 at one time (and still have 3). But in terms of quality, performance and reliability, the AP mount is in a whole different league. It is worth every penny of its price premium over the mass market. I would expect the same to be true of the other premium mounts mentioned here.


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timmbottoni
Carpal Tunnel


Reged: 08/25/05

Loc: W Chicago suburbs, IL USA
Re: Do direct drive mounts really not require guiding? new [Re: WadeH237]
      #6525885 - 05/14/14 10:40 PM

I like the fact that the 10 Micron is supported by Ed at Deep Space Products here in the USA, and I like that AP is made within driving distance of my home. I think either is a good choice.

I am not ready to buy anyway yet, but when I do, I love that I can find so many enthusiast people here on CN to comment on these.

Timm

Edited by timmbottoni (05/14/14 10:46 PM)


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