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Equipment Discussions >> Mounts

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Bart
professor emeritus
*****

Reged: 05/28/06
Posts: 594
Loc: Inside the (DC) Beltway
CGEM plunge.
      #3367206 - 09/30/09 10:19 PM

Well, I did it. I took the plunge and ordered a CGEM. It was a tough call between the CG5 and the CGEM, but the extra weight capacity was the clincher for me. Now all I have to do is order a dual dovetail head unit from ADM so I can mount my scopes on it.

Anyway, I think I’m going to be a happy camper......... if the hand unit doesn’t go south on me. Which brings me to a question. Can I still use a computer to control the mount if the hand unit has been sent back to the manufacturer?

Thanks
Bart

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oldsalt
Astro Philosopher
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Reged: 02/12/05
Posts: 8677
Loc: Pa - between starparties
Re: I took the plunge. new [Re: Bart]
      #3367217 - 09/30/09 10:22 PM

You should be able to

--------------------
There are no winners in war, only bigger losers.

Jim


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Richard Turner
member


Reged: 01/25/09
Posts: 58
Loc: NC
Re: I took the plunge. new [Re: oldsalt]
      #3367387 - 09/30/09 11:31 PM

I had to send my CGEM hand controller to Celestron for warranty work. The display quit working. I sent it on Sept. 8 and received a replacement hand controller on Sept. 29. It works fine.

Richard

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Richard Barton Turner


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BlueGrass
member


Reged: 07/25/09
Posts: 85
Loc: Wasatch Front, UT
Re: I took the plunge. new [Re: Richard Turner]
      #3367467 - 10/01/09 12:00 AM

I also took the plunge and purchased a CGEM. I was hoping to get a GM-11 but just couldn't swing the extra cash this year. So far, my CGEM has worked great, much better performance than my CG5. It handles the 8" SCT, guide scope and 17 + 11 CWs fine. I also used my polar scope from the CG5 and after alignment, it's goto performance was very accurate. After a 4 star alignment, the gotos were almost dead center. It's tracking performance guided was very good. I'm not that adapt in imaging yet but I was able to do multiple 8 minute exposures of M27, M57 and M13 with only one or two unacceptable frames. I tried doing PEC training with the PEC tool but after uploading the averaged runs to the mount, it began a slow creep that could not be corrected by Phd. I had to zero the PEC on the mount to regain control and proper tracking. Right now, PEC is turned off until I can get this resolved. As for the hand controller failures, I've been looking at the angle the cable hangs from the mount. It's not a straight down drop but twists the cable as it hangs above the power inlet. This may be whats causing the HC failures, a damaged cable where it meets the mount RJ12 plug. I've made an extension cable to relieve the awkward pressure on the HC plug. We'll see.

--------------------
Celestron 8" SCT
Orion EON 80 APO
Celestron CGEM/CG5-Adv
Orion ST80 SSAG
Canon 1000D / SBIG ST8300C on order


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donsinger1
sage


Reged: 10/28/07
Posts: 298
Re: I took the plunge. new [Re: BlueGrass]
      #3367636 - 10/01/09 01:43 AM

Don't bother with using PEC while guiding...the CGEM produces fine results without it when guiding...PEC can work against you guiding, just depends on the gear.

--------------------
Fun Stuff:)
Portland, OR


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BlueGrass
member


Reged: 07/25/09
Posts: 85
Loc: Wasatch Front, UT
Re: I took the plunge. new [Re: donsinger1]
      #3368091 - 10/01/09 09:45 AM

Why would PEC work against you while guiding? Isn't PEC supposed to help eliminate worm errors? I don't know if the CGEM applies PEC corrections during or after gear travel. Does this create a battle between the PEC logic in the mount and the autoguider for control? Seems to me that they should work together especially if the averaged PEC corrections uploaded to the mount were taken using the same autoguider.

--------------------
Celestron 8" SCT
Orion EON 80 APO
Celestron CGEM/CG5-Adv
Orion ST80 SSAG
Canon 1000D / SBIG ST8300C on order


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R Nitzel
member


Reged: 01/14/09
Posts: 52
Loc: Corpus Christi, TX
Re: I took the plunge. new [Re: BlueGrass]
      #3368941 - 10/03/09 04:48 PM

PEC smoothed my guiding out considerably. I still get occassionally get a dec drift that PHD can't correct, but its usually from not-quite-good-enough polar alignment. The drift isn't any better or worse with PEC than without, but the graph is smoother with PEC. The guider doesn't care what forces are acting on the mount - if it sees the star move, it tries to compensate. So if PEC smooths out any mount errors and alignment is good, the mount should track more accurately, and the guider should have to make fewer corrections. Theoretically.

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____________________________
Ryan
CGEM 800 Hyperstar 3
Orion ST80
DSI III
SSAG
A lot to learn


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BlueGrass
member


Reged: 07/25/09
Posts: 85
Loc: Wasatch Front, UT
Re: I took the plunge. new [Re: R Nitzel]
      #3369164 - 10/03/09 06:42 PM

R Nitzel,that much pretty summarizes what I've understood PEC was designed to do. If PEC is running, (you can enable / disable it in the HC) then it should help autoguiding, not interfere with it. That is, if the PEC corrections loaded onto the mount are correct in the first place. I haven't had clear skies for the past week or so and haven't had a chance to use PEC tool again. The CGEM built-in PEC routine appears to replace the standalone PEC tool function, i.e. it can train itself during guiding and you can then turn it on and off as necessary. I'm going to try this next time, then download the results with PEC tool to see the difference from the averaged run I initially created with PEC tool. One question I have is can PEC vary depending on OTA load weights? That is, does the worm track differently with a heavier vs. lighter load? In my mind, I think that it would, however slightly. It may be a minuscule variance but it may impact how the mount tracks when you change optical loads.

Richard: When your HC quit working, was it the entire HC or just the display? Was the back light still on?

--------------------
Celestron 8" SCT
Orion EON 80 APO
Celestron CGEM/CG5-Adv
Orion ST80 SSAG
Canon 1000D / SBIG ST8300C on order


Edited by BlueGrass (10/03/09 06:46 PM)


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Richard Turner
member


Reged: 01/25/09
Posts: 58
Loc: NC
Re: I took the plunge. new [Re: BlueGrass]
      #3369398 - 10/03/09 08:39 PM

When the hand control quit working, it was only the display that quit. The back light on the keypad and display window were still on.

The new hand controller came more quickly than expected. So far, it is working just fine.

Richard

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Richard Barton Turner


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BlueGrass
member


Reged: 07/25/09
Posts: 85
Loc: Wasatch Front, UT
Re: I took the plunge. new [Re: Richard Turner]
      #3369469 - 10/03/09 09:29 PM

IF the back light was still working, then you probably just had a loose wire at the RJ12 connector. When I made my HC extension cable, I had two of the interior wires reversed and my HC had the exact same symptoms, i.e. back light on but no characters displayed. Once I found the wiring error and put a new plug on the cable, it worked normally. Your failure somewhat reinforces my opinion that the failures some folks are having are being caused by a bad HC plug / wire connection. Something for folks with CGEMs to consider.

--------------------
Celestron 8" SCT
Orion EON 80 APO
Celestron CGEM/CG5-Adv
Orion ST80 SSAG
Canon 1000D / SBIG ST8300C on order


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donsinger1
sage


Reged: 10/28/07
Posts: 298
Re: I took the plunge. new [Re: BlueGrass]
      #3369675 - 10/03/09 11:27 PM

There is always the potential, when running PEC and guiding simultaneously, that a guide command is countered by a PEC command, thus contributing to drift. It really is dependant on the mount and software. For instance, if it is working for you with the CGEM, great! However, with Gemini systems, it is a known problem that you will get westward drift if you guide and run PEC concurrently. So, it is not black and white. I get great guiding with 5" subs with the CGEM without PEC on, so I figure why add something that can pose a problem...just one persons preference, that's all.

--------------------
Fun Stuff:)
Portland, OR


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chuckscap
sage


Reged: 07/18/09
Posts: 229
Loc: Colorado Springs, CO USA
Re: I took the plunge. new [Re: donsinger1]
      #3371059 - 10/04/09 04:46 PM

Does anyone here have a C11 on a CGEM? I have a Mewlon 250 I need a heavier duty mount for, it's currently on a Vixen Sphinx SXW. The Mewlon just for visual with diagonal, tube counterweight and a 35mm Pan weighs just under 30 lbs. It's a bit longer (about 10" or so) than a C11 also. I will be doing some astrophotography with my modified Canon 300D, but it's primarily a visual setup. I know Celestron put their C11 on a CG5 but I think that was definitely marginal. I may decide to go with a C14 again in the future, will the CGEM handle that as well?


Regards,

Chuck


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BlueGrass
member


Reged: 07/25/09
Posts: 85
Loc: Wasatch Front, UT
Re: I took the plunge. new [Re: chuckscap]
      #3371200 - 10/04/09 06:00 PM

Astronomics lists the C14 as weighing 45 lbs so no, I'd say a basic aluminum C14 itself exceeds the CGEM's list payload capacity. They list the C11 at 27.5 lbs so with a DSLR, guide scope, rings... it will be close to the 40 lb payload listed for the CGEM.

--------------------
Celestron 8" SCT
Orion EON 80 APO
Celestron CGEM/CG5-Adv
Orion ST80 SSAG
Canon 1000D / SBIG ST8300C on order


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Hoosier
journeyman


Reged: 07/29/09
Posts: 5
Re: CGEM plunge. new [Re: Bart]
      #3371250 - 10/04/09 06:29 PM

I'm currently debating to defect to the Celestron CGEM team from the Meade LX200GPS w/wedge. Here is my predicament: I own a 12" Meade SCT w/UHTC, which is a magnificent scope might I add. Downfall is me and the wife would like to travel to more distant star parties (darker skies) and spend less time setting up (story of our lives isn't it?). On a normal imaging night, leveling the mount, getting my bolts and allen wrenches ready, hoisting the OTA alone, getting optics established, conduct drift alignment (good, imaging alignment), and swap out optics with imaging equipment I spend close to 1 1/2hrs,perhaps 2. I don't use a guide scope, so all my images are unguided, hence spending extra time on drift alignment. I can get 60 to 90sec min exposures while keep a crisp image. Because of my long focal length even with a focal reducer star trails are easy to come by. Meanwhile the EQ/GEM enthusiast took a total of 20-30min setting up and are already taking darks and can produce great images at 2-3 minutes exposures. I imagine guided exposures have be something to write home about on these.

This whole "all-sar polar alignment" sounds like a gift from celestial gods themselves. Now that I have the knowledge that aperture isn't critical for CCD imaging, I don't mind downsizing considerably. Keep in mind when I first bought this scope in 2002, CCD imagers were an arm and leg, and all I knew was visual astronomy. Imagers are still expensive in some cases, but perhaps that because our expectations have gone up. The CGEM seems to be appropriate for someone who tends on going to the field often (late or on time), yet will be able to pull off decent some images without cussing at your telescope. I'm not saying GEM's are perfect, but I think most of you know what I mean who have gone from the wedge to GEM.

So what's the plan you say? (Sigh) Well the CGEM looks like a good mount, even though I have read about the HC problems. I would like to get an 8inch SCT, perhaps the HD optics (not so sure on this one yet) or the Meade 8in OTA ACF mounted on that magnificent machinery. I would sell my current scope and mount setup and use those founds to by an SBIG with built-in auto guider, avoiding the guidescope route for awhile. I have a fetish for galaxies, so wide field is not critical for my with exception of M31 of course.

Anyways, I digressed a little, but after seeing how easy the CGEMs setup I had to ask myself. So I was wondering what you guys thought about going from the monster 12" with wedge setup to a friendlier CGEM with 8inch (undecided about Celestron HD or Meade 8in ACF). I have to do something, my current scope is just too big to haul on trips along with my necessary gear with the main purpose of imaging. My wife is afraid I'm going to make her ride on the roof rack of the car to star parties before too long. I'd say I'm about 80/20 in reference astronomy time dedicated to imaging/visual. Keep in mind, Dob scopes and Meade SCT is all I have ever known, hence my posting looking for guidance on converting to CGEM. I even thought about going to refractors, but due my lack of desire for wide field I naturally steer clear. Although it's not a reason to ignore them.

Thanks for input. Bart, let me know how that mount works for you.


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Bart
professor emeritus
*****

Reged: 05/28/06
Posts: 594
Loc: Inside the (DC) Beltway
Re: CGEM plunge. new [Re: Hoosier]
      #3371430 - 10/04/09 08:20 PM

Will do, it's slated to arrive sometime tomorrow.

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BlueGrass
member


Reged: 07/25/09
Posts: 85
Loc: Wasatch Front, UT
Re: CGEM plunge. new [Re: Bart]
      #3371456 - 10/04/09 08:42 PM

Yes, Bart please provide feedback about your new mount and your impressions. I've searched the web alot looking for user feedback or reviews of the CGEM, but there is simply not enough information out there to help current and prospective owners. I've only used mine for 3 nights 10 days ago but it performed very well. In fact, after setup and balancing, it simply got out of the way and allowed me to actually begin spending most of the time deciding on what to image and actually imaging.... For my OTA setup, I was constantly having make sure my CG5 was tracking properly or having to use the Precises goto function in the HC to get the target properly centered in the FOV. The last night of the 3, the CGEM was dead on target and although I used Precise Goto to center the nearby calibration star in the Live View LCD, the CGEM consistently put it INSIDE the LCD focus box. Something my CG5 rarely did.

--------------------
Celestron 8" SCT
Orion EON 80 APO
Celestron CGEM/CG5-Adv
Orion ST80 SSAG
Canon 1000D / SBIG ST8300C on order


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mich_al
super member
*****

Reged: 05/10/09
Posts: 125
Re: CGEM plunge. *DELETED* new [Re: Bart]
      #3371863 - 10/05/09 12:40 AM

Post deleted by mich_al

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Bart
professor emeritus
*****

Reged: 05/28/06
Posts: 594
Loc: Inside the (DC) Beltway
Re: CGEM plunge. new [Re: mich_al]
      #3372147 - 10/05/09 08:32 AM

For what it's worth, your story is the only one that I've read about that has had that type of a deal breaker problem. Most, if not all, have only been about the Hand Controller, and once repaired seem to work fine. I hope your type of experience is few and far in between. Good luck with it, I hope you resolve it to your satisfaction.

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snommisbor
member


Reged: 06/15/09
Posts: 37
Loc: Cedar Park, TX
Re: CGEM plunge. new [Re: Bart]
      #3372915 - 10/05/09 03:50 PM

Ive had mine for about 3 months and it has been great. I take it down to our ranch and the dam close to where I live with a group and from being completely apart to setup it takes me about 20 minutes just taking my time. I havent had any problems and I am glad that this was the scope I bought to jump into this hobby.

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CGEM 800




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Bart
professor emeritus
*****

Reged: 05/28/06
Posts: 594
Loc: Inside the (DC) Beltway
Re: CGEM plunge. [Re: snommisbor]
      #3373121 - 10/05/09 05:33 PM

It came today!

First impressions:

It's big and it's heavy. Oh my aching back!

And unlike the SVP there is a learning curve. Let the reading commence. As soon as I learn a bit about it, I'll be back with my two cents.

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