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Equipment Discussions >> Mounts

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Domerman
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Reged: 07/21/07

Loc: PA
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
scholastic sledgehammer


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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Loc: PA
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

Loc: Bulgaria
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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Reged: 07/21/07

Loc: PA
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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Reged: 01/29/11

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
Just Lucky, I Guess.
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Reged: 07/21/07

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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
scholastic sledgehammer


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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Reged: 08/02/08

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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

Loc: California
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
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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
professor emeritus


Reged: 06/18/08

Loc: Los Angeles
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
sage


Reged: 09/28/12

Loc: Saltsjöbaden, Sweden
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
super member


Reged: 02/11/12

Loc: The Netherlands
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
member


Reged: 12/26/13

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
member


Reged: 08/02/08

Loc: Netherlands
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
Postmaster
*****

Reged: 07/06/07

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
member


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
Refractor wienie no more
*****

Reged: 04/30/03

Loc: NE Ohio
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
Postmaster
*****

Reged: 07/06/07

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
member
*****

Reged: 04/29/12

Loc: Florida
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
Carpal Tunnel


Reged: 08/06/10

Loc: Southern California
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
Refractor wienie no more
*****

Reged: 04/30/03

Loc: NE Ohio
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
super member


Reged: 01/02/10

Loc: Finland
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
member


Reged: 08/02/08

Loc: Netherlands
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 “naked” 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 camera’s 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
member


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
super member


Reged: 01/02/10

Loc: Finland
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
member


Reged: 08/02/08

Loc: Netherlands
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
Pooh-Bah


Reged: 02/24/07

Loc: Snohomish, WA
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

Loc: Saltsjöbaden, Sweden
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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