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Equipment Discussions >> Mounts

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elwaine
Pooh-Bah


Reged: 06/18/06

Loc: Jupiter
Re: IEQ45 - an evaluation new [Re: bardo]
      #4278014 - 12/29/10 11:14 AM

Quote:

yeah im pretty much ONLY interested in how well the mount autoguides personally.




Yes. That is the bottom line. However, you do not specify what types of APs are you interested in, and that can make a BIG difference in which types of mounts (and other equipment) you'll be happy with.

Many questions and comments about APs on this thread are so general in nature that it is not possible to provide meaningful answers. What is it that you (a generic you - no one in particular) want to accomplish with AP? What objects are you interested in? What image scale? What level of commitment in time and energy are you willing to spend learning how to acquire and process images? Are you at, or are you willing to travel to, a dark sky site? And, the BIGGIE, how much money are you able to invest in the hobby? Simply asking one's self "I want to do astro-photography, so what mount and telescope should I buy," is like asking, "should I take my lunch to work, or the bus?" Those questions cannot be answered meaningfully.


Quote:

its PEC graphs that dont mean [as] much when the whole reason for the mount is AP.




That's true only if you don't understand what information PE graphs contain. You cannot fudge PE curves (if the data is collected accurately), but you can "fudge" astro-photos taken under ideal conditions. All you have to do is reduce image scale and/or bin pixels and/or use a camera with larger pixels and/or guide your photos and/or use an adaptive optics device (like an AO-8), and /or keep your subs in the 2-3 min range. All of the above - singly, but especially in combination - will result in very nice astro-photos containing no visible star trails even when the inherent performance of a mount is just OK, rather than being very good.


Quote:

there is no such thing as a mount that doesnt require autogiuding, even ASA users apparently still use it.




I beg to differ with you. There are many mounts that will allow you to obtain unguided exposures for 5 or 10 minutes (at the very least) with results that are even better than the guided exposures we've seen using the IEQ45. The problem is that those mounts are very expensive.

As to why folks still guide using expensive mounts (like the direct drive ASA mounts)... there could be a number of reasons. They may be acquiring images using very long exposure times rather than 5 or 10 minute subs (a mistake, IMHO... but that's way off topic), or they may want to use very large image scales, or they may be interested in over sampling (for a number of reasons), or they may not have a permanent observatory and do not have their mounts in perfect polar alignment, etc., etc., and so on....


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elwaine
Pooh-Bah


Reged: 06/18/06

Loc: Jupiter
Re: IEQ45 - an evaluation new [Re: elwaine]
      #4278158 - 12/29/10 12:44 PM

Getting back to the IEQ45...

I commented previously about the relative difficulty in adjusting the AZ. and ALT. motions of the mount during the polar alignment process. One proposed solution to having the AZ. move easily was to use teflon tape on the contact surface of mount head and tripod. I was going to try that but then, Don Pensack (Starman1) suggested that I sand off all paint that is on the contact surfaces.

I used 400 and then 600 grit sandpaper to remove the paint from both surfaces, and the ease of motion improved. Then I used John Miele's suggestion and applied a thin film of Super Lube to the contact surfaces and the AZ motion is now smooth and easy... and still locks up tight after adjustment.

The ALT adjustment is still too difficult - and the short adjustment pin that iOptron supplies to help move the mount head in ALT is way too short to provide sufficient leverage to lift the mount head in ALT. The problem seems to be the ALT mechanism itself. There is too much play between the brass screws and the wheel that moves the mount head up and down, and the wheel seems to bind on the screws. It's no problem when there is no equipment on the mount. But add 15 to 30 lb. of equipment and adjusting ALT during polar alignment is at best a difficult, jerky procedure.



I've replaced the short ALT pin with a longer screw to get more leverage. It's not quite the right tool. I do not want anything that has to be screwed in and out, but rather one that is held in place by friction, so that it can easily be moved from one hole to another.


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Starman1
Vendor (EyepiecesEtc.com)
*****

Reged: 06/24/03

Loc: Los Angeles
Re: IEQ45 - an evaluation new [Re: elwaine]
      #4278417 - 12/29/10 03:01 PM

Try some of the Superlube on the threads of the bolt and on the turning end of the altitude bolt.
That will reduce the force necessary, and the jerkiness.
Then replace the screw with a pin that can be moved from hole to hole, or machine a larger knob for the adjustment knob on the bolt.
I bet the grease makes it easy and smooth.
If the threads on the bolt are rough and poorly cut, I have also found that taking the bolt to a wire wheel with often smooth things out a lot.


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TrevorW
sage


Reged: 06/21/08

Loc: Western Australia
Re: IEQ45 - an evaluation new [Re: Starman1]
      #4278989 - 12/29/10 08:30 PM

I might wait for the next version

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John Miele
Carpal Tunnel
*****

Reged: 05/29/05

Loc: North Alabama
Re: IEQ45 - an evaluation new [Re: elwaine]
      #4279038 - 12/29/10 09:04 PM

Quote:

Getting
The ALT adjustment is still too difficult - and the short adjustment pin that iOptron supplies to help move the mount head in ALT is way too short to provide sufficient leverage to lift the mount head in ALT. The problem seems to be the ALT mechanism itself. There is too much play between the brass screws and the wheel that moves the mount head up and down, and the wheel seems to bind on the screws. It's no problem when there is no equipment on the mount. But add 15 to 30 lb. of equipment and adjusting ALT during polar alignment is at best a difficult, jerky procedure.





Hi Larry,

I am surprised the altitude adjustment is problematic for you. It works very smoothly on my mount with the C8 and 2 CW on board. It's possible the threads may be a little rough on your adjustment screw. Polishing the threads and adding a little superlube will probalby be a great help...John


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elwaine
Pooh-Bah


Reged: 06/18/06

Loc: Jupiter
Re: IEQ45 - an evaluation new [Re: John Miele]
      #4279682 - 12/30/10 08:26 AM

Thanks John,

I applied Super Lube . Seems to be better but haven't tried it under load yet.


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vdb
sage


Reged: 12/08/09

Re: IEQ45 - an evaluation new [Re: elwaine]
      #4299923 - 01/08/11 07:21 AM

Been quiet lately, so here is a question,
is there a PE measure when guiding, I only saw raw data or PEC adjusted data, the reason I ask is that whatever the error is I'm interested in the error with guiding.
I have a G8 and G11, G8 has a peak to peak eeror of 20, but guides out at around 2 arcsec, the G11 has 7 but guides around 3 to 4 ... so better unguided worse guided ...


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elwaine
Pooh-Bah


Reged: 06/18/06

Loc: Jupiter
Re: IEQ45 - an evaluation new [Re: vdb]
      #4300004 - 01/08/11 08:38 AM

Excellent point! I've been waiting for a clear night to test that very thing myself. However, as I'm sure you know, results will vary depending on a variety of factors, including the brightness of the guide star, etc. Still, knowing what the error curve looks like during guiding will be provide valuable information for those who will use the IEQ45 as a guided mount.

Stay tuned. I'll try to get that data during the next few days - weather permitting.


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Nocturnal
Carpal Tunnel
*****

Reged: 09/14/05

Loc: CT, USA
Re: IEQ45 - an evaluation new [Re: vdb]
      #4300213 - 01/08/11 10:33 AM

I agree this is the measure this ultimately matters the most. The problem is that guiding itself can be done well or poorly. So a set of guiding parameters that are not optimal for a particular setup (mount, pier, equipment) can make the mount look worse than it is.

I think that raw PE curves and PEC corrected PE curves give people an idea about the inherent quality of the mount. Guided PE curves give you an indication of what's possible but only that. Your own guiding may be better or it may be worse.

Recording guided PE curves is the best way to evaluate guide settings once you're beyond just getting the thing to guide at all. Correlate the sway of the beam to the size of your pixels and you have a real idea how much smudging is happening.


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vdb
sage


Reged: 12/08/09

Re: IEQ45 - an evaluation new [Re: Nocturnal]
      #4300397 - 01/08/11 12:28 PM

I trust on the skills of Larry, but yes it also depends on a lot of factors, but it's important to know how accurate you can guide a mount, some are really very hard to manage ... even if all parameters are ideal/correct ...
Remember all the stories about dec guiding issue on the cg5 and to a lesser extend the cgem ... and the 76 sec jump on some of the losmandy ...


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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: IEQ45 - an evaluation new [Re: vdb]
      #4300441 - 01/08/11 12:49 PM

Quote:

I have a G8 and G11, G8 has a peak to peak eeror of 20, but guides out at around 2 arcsec, the G11 has 7 but guides around 3 to 4 ... so better unguided worse guided ...






Hi vdb,

Any ideas why these counterintuitive results in your case?

Gale

Edited by gdd (01/08/11 04:07 PM)


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Nocturnal
Carpal Tunnel
*****

Reged: 09/14/05

Loc: CT, USA
Re: IEQ45 - an evaluation new [Re: vdb]
      #4300553 - 01/08/11 01:47 PM

Very long PE recordings will reveal any local roughness in the gears. That will tell you something about the consistency of the mount.

If a guided PE recording has long excursions then it's possible the guider went haywire. It'll be hard to determine that even if you're watching the whole session closely as it happens. These types of excursions do not necessarily reflect poorly on the mount. It could be caused by any number of factors.


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vdb
sage


Reged: 12/08/09

Re: IEQ45 - an evaluation new [Re: gdd]
      #4300623 - 01/08/11 02:29 PM

Quote:


Hi vlb,

Any ideas why these counterintuitive results in your case?

Gale




For the moment not, it seems though the G8 has a larger Peak-to-peak it seems smoother ... not as sudden ... but need more testing.

This is why I'm also interested in PE with guiding.


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gdd
Pooh-Bah


Reged: 11/23/05

Loc: N Seattle suburb, WA
Re: IEQ45 - an evaluation new [Re: vdb]
      #4300805 - 01/08/11 04:02 PM

Quote:

For the moment not, it seems though the G8 has a larger Peak-to-peak it seems smoother ... not as sudden ... but need more testing.

This is why I'm also interested in PE with guiding.






Hi vdb,

I think this would be an interesting new thread to compare a high PE GM-8 that guides better than a low PE G-11.

Gale

Edited by gdd (01/08/11 04:06 PM)


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elwaine
Pooh-Bah


Reged: 06/18/06

Loc: Jupiter
Re: IEQ45 - an evaluation [Re: gdd]
      #4301706 - 01/09/11 12:21 AM

I was able to record the PE during guiding. Results are interesting. (It's late and I'm too tired to post the graphs now, but I will post them tomorrow.)

Maxim DL allows fine adjustments of mount motion during guiding. The general aggressiveness (or guiding responsiveness) of each axis, as well as the backlash control of each axis, can be individually adjusted. Mount motion during calibration can be seen on-screen and makes it easy to see how changes in aggressiveness and backlash affect mount movements.

I ran only two sets of data. The first run was for nearly 3 full worm cycles. No compensation for RA backlash was used but the Dec backlash compensation was set at roughly 4 on a scale of 1-10. The aggressiveness settings for both axes were at the low end of the range. That run reduced the PE from 30 arc seconds peak to peak down to 15 arc seconds peak to peak.

I then increased the DEC backlash compensation and set it to 6. I made no changes in the general aggressiveness settings. The PE droped to only 7 arc seconds peak to peak.

I can probably fine tune the adjustments to lower the PE even further, but for my purposes, a guided PE of + or - 3.5 arc" will work quite nicely.


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vdb
sage


Reged: 12/08/09

Re: IEQ45 - an evaluation [Re: elwaine]
      #4301849 - 01/09/11 03:33 AM

Hi Larry,
thanks for being so quick ...
Interesting results, if other owners IEQ45 owners can do the same test, that would give us a goo idea on how this mount would keep up for AP.

(I'm happy to see my G8 can keep up, was wondering if a swap was in order, maybe it still is as I wan't goto back ...)


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elwaine
Pooh-Bah


Reged: 06/18/06

Loc: Jupiter
Re: IEQ45 - an evaluation [Re: vdb]
      #4302023 - 01/09/11 08:41 AM

This was an exercise in POOR PLANNING and loss of concentration. The only lessons I learned from this are 1) that one should plan ahead; and 2), one should avoid conversation with curious neighbors while trying to set up experimental conditions that were not well planned in advance and were not written down!

I used my C9.25. Total load was about 28 lbs. Seeing was just average - maybe 3 on a 1-5 scale. I had intended to bin the guide chip to better match seeing conditions, but I forgot to do so, and wound up using an image scale of less than 1 arc second per pixel - way too high! That alone casts doubts on what the following graphs show.

In each case, the guide star stayed centered within the real-time tracking window. So I'm not sure what the graphs mean. I should have taken an image while I was recording the PE data. The combination of an image and a PE graph would have had much more meaning than the graphs alone. Oh well... next time. (I suppose I am incapable of talking and thinking at the same time. With skills like that, I should have gone into politics! )




Quote:

I'm happy to see my G8 can keep up, was wondering if a swap was in order, maybe it still is as I wan't goto back ...




Did you really have any doubts? If you can keep the equipment weight load below 30 lb., a GM8 should out-perform the IEQ45. But you'll spend over $1,000 more for a GM8 that has all the features of an IEQ45. Quality never comes cheap! (Personally, I think that an extra $1,000 - $1,200 is worth the expenditure for those who can afford a complete GM8 package.)

The IEQ45 works OK at least with loads up to about 30 lb. While I haven't tested it at greater loads, I think the 45 lb. stated carrying capacity will prove to be overly optimistic.


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Midnight Dan
Postmaster
*****

Reged: 01/23/08

Loc: Hilton, NY, Yellow Zone (Bortl...
Re: IEQ45 - an evaluation [Re: elwaine]
      #4302253 - 01/09/11 11:11 AM

Quote:

The IEQ45 works OK at least with loads up to about 30 lb. While I haven't tested it at greater loads, I think the 45 lb. stated carrying capacity will prove to be overly optimistic.




It's been my impression that on any mount, the max capacity rating is for visual use. For imaging, I'm told that the ideal is to use half the capacity, 2/3 at most. Based on that, imaging on this mount should be great at loads in the low 20s and should be acceptable up to around 30 pounds.

Sounds consistent with your experiences so far.

-Dan


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elwaine
Pooh-Bah


Reged: 06/18/06

Loc: Jupiter
Re: IEQ45 - an evaluation [Re: Midnight Dan]
      #4302291 - 01/09/11 11:24 AM

Quote:

Quote:

The IEQ45 works OK at least with loads up to about 30 lb. While I haven't tested it at greater loads, I think the 45 lb. stated carrying capacity will prove to be overly optimistic.




It's been my impression that on any mount, the max capacity rating is for visual use. For imaging, I'm told that the ideal is to use half the capacity, 2/3 at most. Based on that, imaging on this mount should be great at loads in the low 20s and should be acceptable up to around 30 pounds.

Sounds consistent with your experiences so far.

-Dan





I agree with most of what you say, Dan. But there are some top tier mounts (such as A-P's line) that can guide right up to their maximum rated load. Of course, you'll have to pay a premium for that kind of performance. - I wish the IEQ45 performed like a $6,000 mount. Then again, I wish I performed as well as a $6,000 mount. All one can ask is that we get what we pay for, and I think that the IEQ45 is probably worth its price. (The problem, for me, is that having once owned 2 A-P mounts, I am spoiled.)


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TDM
Vendor, MDA-Telescoop


Reged: 08/24/10

Loc: Hungary, Europe
Re: IEQ45 - an evaluation *DELETED* [Re: elwaine]
      #4302921 - 01/09/11 04:38 PM

Post deleted by Bowmoreman

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