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Hogarthd
newbie

Reged: 12/25/08

Re: The ultimate CGEM topic ... new

new

[Re: mclewis1]
#2983361 - 03/14/09 12:27 PM

I've been lurking on this forum for awhile now in anticipation of upgrading my Nexstar 8se for a CGEM-1100 in May or June. I'm just curious if any of you guys are using the CGEM with a c11 OTA. Is this mount substantial enough for visual and photographic use with that much weight on it? To be honest, I'm sort've waffling between the CGEM-1100 and the CGEM-925. I want more aperature, but my current Nexstar 8 is maddeningly wobbly on its single-arm fork mount.

thanks!

Hogarth de la Plante
Oakland, CA

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mclewis1
Thread Killer

Reged: 02/25/06

Loc: New Brunswick, Canada

Re: The ultimate CGEM topic ... new

new

[Re: Hogarthd]
#2983539 - 03/14/09 01:59 PM

Hogarth,

Welcome to CN (well as a poster anyway

)

I'm not sure I'd want to do a lot of imaging with a 2850mm C11 on a CGEM. At the very least I'd want to use a focal reducer to bring this down to a more manageable 1800mm or so. I'd also work to keep the weight down as much as possible, so I'd look into a very small autoguiding setup. Something like the homemade 50mm finder/Orion SSG combinations, or the commercial version, the Kwiq guider from KW Telescope Kwiq guider.

In the short term though you might consider simply buying a CGEM by itself and using your C8 on that mount. Maybe get the Losmandy D to vixen adapter, or replacement saddle, or the side by side saddle so you can mount a small refractor beside your C8 (which would make for a really great setup).

I really like the combination of a 8SE for grab n go observing and the CGEM for imaging and more planned observing sessions. I know the "sickness" of aperture fever for visual work but you should really try and avoid it for imaging ... you'll get much better results from a smaller aperture lighter weight setup that tracks perfectly than a bigger aperture heavier config that may not track as well. If everything goes well with the C8 on the CGEM then maybe move up to a C9.25 or C11 in the future ... by then you'll also have all kinds of practical imaging knowledge which could really help you with those bigger scopes.

As for your SE, have you tried some add ons such as extra weight to the tripod spreader bar, anti vibration pads, and a Feathertouch SCT microfocuser to exorcise those "wigglies"?

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Dr Benway
professor emeritus

Reged: 03/27/08

Loc: Abilene, TX

Re: The ultimate CGEM topic ... new

new

[Re: mclewis1]
#2983549 - 03/14/09 02:04 PM

Pull the C8 out of the Nexstar mount and use it on the CGEM. Buy a QHY8 camera with what you would have spent on the C11.

John

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Hogarthd
newbie

Reged: 12/25/08

Re: The ultimate CGEM topic ... new

new

[Re: Dr Benway]
#2984368 - 03/14/09 09:58 PM

Thanks for the good advice, guys. Part of my reason for upgrading the scope itself is that the primary mirror has a small scratch on it. I "inherited" the 8se from a good friend of mine a couple of years ago and while attempting to collimate it the first time, having no knowledge of what I was doing, I accidentally unscrewed the secondary mirror causing it to fall into the OTA and scratch the primary. I reassembled it, taking care to keep the corrector in alignment and, somehow, the performance doesn't seem terribly affected. However, I can't help that niggling feeling that for the last two years of usage, it hasn't been performing as well as it should.

I'd like to pick up a CGEM to learn my way around a GEM mount for a summer of visual observing and then try my hand at AP in a year. Maybe I should look into the less expensive CGEM-925 or CGEM-800 and put any extra money aside for imaging gear at a later date.

thanks again, guys -

Hogarth

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rawhead909
member

Reged: 06/26/08

Loc: Boston, MA

Re: The ultimate CGEM topic ... new

new

[Re: Hogarthd]
#2984609 - 03/15/09 01:16 AM

Hi guys; I'm looking to jump on the CGEM bandwagon sometime later this year, when I have more time, money, and, I guess better chance of purchasing one and getting it within 6 months :-)

Anyway, as far as OTAs go, I have a C8 and a Megrez 90; would a side-by-side setup with these two work well for imaging, without putting too much stress on the mount?

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Martin Lyons
sage

Reged: 10/06/08

Loc: Cape Town, South Africa

Re: The ultimate CGEM topic ... new

new

[Re: Lane]
#2984696 - 03/15/09 03:25 AM

Quote:

You know this for a fact?

From measurements I have taken on my Atlas NEQ6 tripod and comparing my measurements with the image posted previously in this thread, I am confident that the Atlas NEQ6 tripod head and the CGEM tripod head are identical.

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Olivier Biot
Amused

Reged: 04/25/05

Loc: 51°N (Belgium)

Re: The ultimate CGEM topic ... new

new

[Re: Hogarthd]
#2984754 - 03/15/09 05:27 AM

Quote:

Part of my reason for upgrading the scope itself is that the primary mirror has a small scratch on it. I "inherited" the 8se from a good friend of mine a couple of years ago and while attempting to collimate it the first time, having no knowledge of what I was doing, I accidentally unscrewed the secondary mirror causing it to fall into the OTA and scratch the primary. I reassembled it, taking care to keep the corrector in alignment and, somehow, the performance doesn't seem terribly affected. However, I can't help that niggling feeling that for the last two years of usage, it hasn't been performing as well as it should.

How bad it may look, many scratches go unnoticed most of the time. One thing you can do for reducing the effect of this scratch on image quality is having the scratch blackened with flat black paint. Use a small tipped brush for this job - plastic modeling enamel paint brushes will do fine.

If you're not convinced: try computing the area covered by the scratch (usually only a couple mm²). For most mirror diameters this loss of reflective surface is impossible to detect. I'm not sure you will even be able to see contrast differences due to this one scratch.

By the way, you may want to inspect the edge of the secondary mirror to look for dents at the edge. You can mask those edges the same way with flat black paint.

You can always ask for advice on this matter in the Reflectors board or in the ATM board.

Cheers,

Olivier

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phanf4
super member

Reged: 07/31/07

Loc: Over there in Chattanooga

Re: The ultimate CGEM topic ... new

new

[Re: rawhead909]
#2984776 - 03/15/09 06:07 AM

Quote:

Hi guys; I'm looking to jump on the CGEM bandwagon sometime later this year, when I have more time, money, and, I guess better chance of purchasing one and getting it within 6 months :-)

Anyway, as far as OTAs go, I have a C8 and a Megrez 90; would a side-by-side setup with these two work well for imaging, without putting too much stress on the mount?

Im waiting on this answer also.

Tom

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mclewis1
Thread Killer

Reged: 02/25/06

Loc: New Brunswick, Canada

Re: The ultimate CGEM topic ... new

new

[Re: phanf4]
#2985526 - 03/15/09 03:27 PM

Quote:

Anyway, as far as OTAs go, I have a C8 and a Megrez 90; would a side-by-side setup with these two work well for imaging, without putting too much stress on the mount?

C8 - 13lbs
M90 - 11lbs(guess)
Vixen side by side saddles - 3lbs
Rings on a rail (for the M90) - 3lbs
Cameras (primary and autoguider) - 2lbs
Misc (finderscope, etc.) - 1 lb

33lbs total.

Can the mount handle it for visual, sure. For imaging, yes but ... you'll likely be happier with a lighter setup for imaging ... maybe consider a compact 50mm finder/autoguider setup in place of the M90 and rings when imaging with the C8. That change could save you about 10lbs.

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Lane
Post Laureate

Reged: 11/19/07

Loc: Frisco, Texas

Re: The ultimate CGEM topic ... new

new

[Re: Martin Lyons]
#2985893 - 03/15/09 07:03 PM

Quote:

Quote:

You know this for a fact?

From measurements I have taken on my Atlas NEQ6 tripod and comparing my measurements with the image posted previously in this thread, I am confident that the Atlas NEQ6 tripod head and the CGEM tripod head are identical.

I started another thread on this topic a few days ago. The answer is that the Atlas and CGEM tripod mounting holes are identical. Verified by OPT, they actually mounted the tripod extension on their display CGEM to make sure it would work.

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PhilCo126
Carpal Tunnel

Reged: 01/14/05

Loc: coastline of Belgium

Re: The ultimate CGEM topic ... new

new

[Re: Lane]
#2987105 - 03/16/09 02:08 PM

Another 3 weeks and I'll have mine

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waassaabee
Post Laureate

Reged: 11/26/07

Loc: Central California Coast

Re: The ultimate CGEM topic ... new

new

[Re: PhilCo126]
#2987117 - 03/16/09 02:16 PM

That's the same timeframe for mine!!

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Dr Benway
professor emeritus

Reged: 03/27/08

Loc: Abilene, TX

Re: The ultimate CGEM topic ... new

new

[Re: waassaabee]
#2987343 - 03/16/09 04:42 PM

Gary and PhilCo,

Do you have relatives working for Celestron? Mine has been on order since February 3rd, and it has always been 3 weeks away.....

John

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waassaabee
Post Laureate

Reged: 11/26/07

Loc: Central California Coast

Re: The ultimate CGEM topic ... new

new

[Re: Dr Benway]
#2987368 - 03/16/09 04:52 PM

John,

We don't have them yet....

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Lord Beowulf
Pooh-Bah

Reged: 10/13/08

Loc: Cedar Park, TX

Re: The ultimate CGEM topic ... [Re: waassaabee]
#2987575 - 03/16/09 07:02 PM

I noticed my latest delay notification was not the usual "Your CGEM will arrive around..." message, but rather, "We do not expect to receive a CGEM shipment before...".

Beo

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mclewis1
Thread Killer

Reged: 02/25/06

Loc: New Brunswick, Canada

Re: The ultimate CGEM topic ... [Re: Lord Beowulf]
#2987652 - 03/16/09 07:36 PM

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rawhead909
member

Reged: 06/26/08

Loc: Boston, MA

Re: The ultimate CGEM topic ... [Re: mclewis1]
#2989993 - 03/18/09 04:35 AM

Mark,

Thanks for the breakdown. I get the gist. Whatever the caase, I do feel that my setup (C8, Megrez 90, and assortment of DSLR + lenses) is perfect for a CGEM system. Can't wait to get my hands on one :-)

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PhilCo126
Carpal Tunnel

Reged: 01/14/05

Loc: coastline of Belgium

Re: The ultimate CGEM topic ... [Re: rawhead909]
#2990410 - 03/18/09 11:24 AM

In Europe, quasi all suppliers are out of stock and the CGEM will be plenty available during the Easter holidays... what a better gift to wish

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PhilCo126
Carpal Tunnel

Reged: 01/14/05

Loc: coastline of Belgium

Re: The ultimate CGEM topic ... [Re: PhilCo126]
#2996418 - 03/21/09 02:46 PM

Just learned that this half pillar will fit for the CGEM:
half pillar for EQ-6

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Trever
Post Laureate

Reged: 08/18/03

Loc: North Alabama

Re: The ultimate CGEM topic ... [Re: Hogarthd]
#2996474 - 03/21/09 03:08 PM Attachment (98 downloads)

Quote:

I've been lurking on this forum for awhile now in anticipation of upgrading my Nexstar 8se for a CGEM-1100 in May or June. I'm just curious if any of you guys are using the CGEM with a c11 OTA. Is this mount substantial enough for visual and photographic use with that much weight on it? To be honest, I'm sort've waffling between the CGEM-1100 and the CGEM-925. I want more aperature, but my current Nexstar 8 is maddeningly wobbly on its single-arm fork mount.

I cannot speak for a true master of these mounts, but so far It seems rock solid especially compared to the Cg5. It comes with two 17 lb weights and when the legs are in the lower extension, feels sturdy. I did not notice any kind of problem with dampening. My issue right now is with the C11 OTA as I seem to have some image shift when focusing. But that is another topic.

I have only had the chance to use it outdoors once and had it setup in my house to work with the alignment procedures. But this mount is worlds better than the CG5 for an OTA of this weight. My CG5 will need the new hand controller to be broght up to the new updates though. I included a pic of the 2 systems side by side.

I am interested in getting the Atlas extension for the mount. Someday. I would like to get an F/12 D&G refractor to use with is for visual viewing. Maybe that is a pipedream, but supposedly, the mount should be beefy enough for it.

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