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CGEM: What's the truth?

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#51 kpendlebury

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Posted 27 April 2010 - 03:18 PM

I have had my CGEM for about 10 months now and have take quite a few images with it at short FLs (http://www.flickr.com/photos/kenastro/). Based on testing and use, I would be a little timid about using the CGEM for imaging at longer focal lengths. My peak to peak PE comes in at about 43 arc seconds (I have seen reports up to 55 - 60 arc-seconds) and seemed to train out well coming in a 6.3 arc-seconds peek to peek. I am not complaining here... for $1400 this mount performs admirably.

Obviously, the blue curve is corrected and the red curve is out of the box PE:

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#52 rmollise

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Posted 27 April 2010 - 04:15 PM

I have had my CGEM for about 10 months now and have take quite a few images with it at short FLs (http://www.flickr.com/photos/kenastro/). Based on testing and use, I would be a little timid about using the CGEM for imaging at longer focal lengths.


6.3 arc-seconds without guiding and you would be timid to use it at longer focal lengths? Why?

#53 Trox

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Posted 27 April 2010 - 05:27 PM

Tom H. still has my CGEM and is communicating several times a week, with long notes and photos of the interior parts.


Hi tedbnh,
Care to share some of those pic's of the interior of the CGEM? I'm about to buy a CGEM, but stumbled across some post about the gear's material (Gearbox).
/Trox

#54 Jeff55

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Posted 27 April 2010 - 07:01 PM

I've got mine loaded to almost maximum capacity and it just works. Even fit and finish is excellent. In its' price range it is absolutely unbeatable. I love it!

#55 kpendlebury

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Posted 28 April 2010 - 12:08 PM

6.3 arc-seconds without guiding and you would be timid to use it at longer focal lengths? Why?


You have a fair point Rod. My problems are likely not mount related, but rather user related. I still have trouble with exposures greater than 5 minutes, but this might be due to my own inexperience, polar alignment issues or with differential flexure.

#56 Bart

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Posted 21 January 2011 - 01:18 PM

Interesting thread. Thanks Jim.

#57 Ad Astra

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Posted 21 January 2011 - 02:50 PM

I have a CGEM-11 at work for the kids to use in astronomy class. It works great and tracks fine. We don't do a lot of astrophotos on it, though - so I can't say much about photographic performance.

Fit, finish, and reliability have been fine over the last 18 months, and as you may imagine with it being a 'school' instrumnet, it doesn't always get treated with the utmost care it deserves.

Overall, I've been really pleased, and for visual work, I'd recommend one to a friend or buy one again.

This being said, the mount is about at it's limit for weight with a C11. I've mounted my big refractor (40+ lbs, f/12 monster) and it causes the mount to strain and the wobble and vibration dampening to shoot through the roof to totally unacceptable levels.

Dan






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