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Equipment Discussions >> Mounts

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Guillermo
journeyman


Reged: 09/18/07

Celestron CGEM or Losmandy GM8? new
      #3641551 - 02/22/10 09:10 PM

Greetings,
I need to upgrade my mount for astrophotography. My setup includes a Televue NP101is scope and the new SBIG ST8300 camera. My old AS-GT was fine for observing but less than acceptable for imaging.
At first, I was quite convinced that the Losmandy GM8 was the obvious choice (given my budgetary constraint) but then I started reading pretty bad reviews on backlash and other issues that require manipulating the mount prior to acceptable use. In my case, I would like to have a mount to spend more time imaging and less tweaking the mount.
How does the Celestron CGEM perform for guided astrophotography. Any known issues?

Thanks!


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gnowellsct
Postmaster
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Reged: 06/24/09

Re: Celestron CGEM or Losmandy GM8? new [Re: Guillermo]
      #3641598 - 02/22/10 09:37 PM

We've had some remarkable posts lately of 6 arc second peak to peak G11s out of the box.

The needs-to-tinker rate will not be less on a Celestron mount than on a Losmandy. Regrettably, the needs-to-tinker factor is very difficult to escape. The less you spend the more you need to tinker.

For photography you have the Ovision option with the Losmandy line. That's a powerful upgrade for not much money.

http://www.astromart.com/articles/article.asp?article_id=663

But I think it's worth the money in the end to get the G11 rather than the g8. The thing is, you've got this nice four inc h scope, you get a G11 you can throw a 9.25 Edge on there and do all sorts of fun stuff, so you can move in both the wide field domains with your refractor and upgrade to a 9.25, a powerful chunk of aperture, and both ride well on the G11.

regards
Greg N


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Guillermo
journeyman


Reged: 09/18/07

Re: Celestron CGEM or Losmandy GM8? new [Re: gnowellsct]
      #3642082 - 02/23/10 06:09 AM

Thank you Greg for your reply.
Indeed, I have read another post claiming that the Celestron CGEM has 50 or even 60'' PEC. If true, that is way out of acceptable levels.
If I can narrow the Losmandy to less than 10'' I would be satisfied.
Now, for the G11, unfortunately, my budget will not allow it, especially if I consider the Gemini system.
The thing is, I am comparing the GM8 with Gemeni with the CGEM. In such a frame, the question is whether the Losmandy is worth the extra USD 1000?

Guillermo


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RTLR 12
Post Laureate
*****

Reged: 12/04/08

Loc: The Great Pacific NorthWest
Re: Celestron CGEM or Losmandy GM8? new [Re: Guillermo]
      #3642108 - 02/23/10 06:42 AM

Don't believe everything you read...My CGEM's at 9.

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Phil Cowell
Carpal Tunnel
*****

Reged: 05/24/07

Loc: Southern Tier NY
Re: Celestron CGEM or Losmandy GM8? new [Re: Guillermo]
      #3642134 - 02/23/10 07:13 AM

The CGEM would work very well. You also know the controller from your ASGT and wouldn't be losing any features you already know with the CGEM.
As for the $1300 Vs $3100 + $500 if you want the Ovision upgrade that the G11 would cost with goto capabilities you'd have to justify if that was worth the financial cost and the time investment to learn another goto system. You can also find a CGE for around $2600 if I remember OPT had a sale on them. There are some great images with a 4" APO and a CGEM/Atlas on the net.


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drksky
Carpal Tunnel
*****

Reged: 09/01/09

Loc: Bloomington, IL
Re: Celestron CGEM or Losmandy GM8? new [Re: Phil Cowell]
      #3642167 - 02/23/10 07:51 AM

Quote:

You can also find a CGE for around $2600 if I remember OPT had a sale on them.




Not any more (new, anyway). Opt had two CGEs in stock when I bought mine last week, now they're not even listed on the site.

There were a couple used ones on AM last week selling for just a little less than a new GM-8 /w Gemini.


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Guillermo
journeyman


Reged: 09/18/07

Re: Celestron CGEM or Losmandy GM8? new [Re: RTLR 12]
      #3642186 - 02/23/10 08:05 AM

Quote:

Don't believe everything you read...My CGEM's at 9.



That's interesting. How many hours of PEC training did it take you to get it down to 9? Or was it just out of the box?


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RTLR 12
Post Laureate
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Reged: 12/04/08

Loc: The Great Pacific NorthWest
Re: Celestron CGEM or Losmandy GM8? new [Re: Guillermo]
      #3642451 - 02/23/10 10:46 AM

Out of the box.

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waassaabee
Postmaster
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Reged: 11/26/07

Loc: Central California Coast
Re: Celestron CGEM or Losmandy GM8? new [Re: RTLR 12]
      #3642582 - 02/23/10 11:38 AM

I haven't measured my CGEM's PE, but I can get 7 minute frames @1625mm all night long while guiding.

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mish
sage


Reged: 02/10/09

Loc: West of Astronomics
Re: Celestron CGEM or Losmandy GM8? new [Re: Guillermo]
      #3643034 - 02/23/10 03:01 PM

Quote:


At first, I was quite convinced that the Losmandy GM8 was the obvious choice (given my budgetary constraint) but then I started reading pretty bad reviews on backlash and other issues that require manipulating the mount prior to acceptable use.




As much as I appreciate the quality and performance and general idiot-proofness of my Losmandy G11 mount, I don't see the value of a GM8 in comparison with a CGEM for your purposes, especially if you want a GoTo system. With GoTo, the GM8 is over $1000 more than the CGEM, and since you mentioned budget constraints, that's hard to justify.

If you don't use GoTo, the prices are closer, and Losmandy's mounts have excellent mechanical qualities (i.e., one can tinker with them, but the box-stock performance is excellent without any tinkering), and the fit and finish of the GM8 is of very high quality. But that's comparing the GoTo-less GM8 to the GoTo CGEM. If GoTo is important to you, then this sounds to me like an easy decision.


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Guillermo
journeyman


Reged: 09/18/07

Re: Celestron CGEM or Losmandy GM8? new [Re: mish]
      #3644389 - 02/24/10 06:21 AM

Quote:


As much as I appreciate the quality and performance and general idiot-proofness of my Losmandy G11 mount, I don't see the value of a GM8 in comparison with a CGEM for your purposes, especially if you want a GoTo system.




Yes, I think goto is a must these days for astrophotography not just because you can easily move from object to the next but it will give you the option of adding software assisted improvements for your mount such as pinpoint or pempro. Furthermore, you can automize some tasks and use a remote laptop to control the entire setting (of course, including the mount). Using a goto mount, you can also use a digital drift alignment method such as Bigourdan with your CCD camera. It's easy, you have total laptop control.
Finally, I have read that the Losmandy (without the Gemini) will not record the PEC after power off. The Gemini system, on the other hand can keep track of PEC session after session, improving the tracking capabilities of the mount. (Does the CGEM do the same?)
In summary, I would rule out any non goto mount even if I am an old fashion deepsky observer (i.e., I use my star charts to locate objects)


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Charlie HeinAdministrator
Postmaster
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Reged: 11/02/03

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Re: Celestron CGEM or Losmandy GM8? new [Re: Guillermo]
      #3644408 - 02/24/10 07:01 AM

The CGEM would be the way to go then - or as an alternate you might consider the EQ6/Orion Atlas with the EQMOD ASCOM driver. The driver (along with a small hardware module that you can either build or buy from Shoestring Astronomy) completely replaces the hand paddle and runs all aspects of mount control. It has a very complete feature set and works very well with most ASCOM compatible planetarium software, as well as Maxim DL. It's also aggressively under development to refine and add new features. We have a large number of Atlas owners in my astronomy club who use EQMOD and I don't know of a single one who doesn't really like it - in fact a couple of them haven't used the stock hand controller in so long that they don't even know where they left it.

That said, if you are well familiar with the newer ASGT handbox there would be nearly zero learning curve with the CGEM. The two mounts are nearly identical in performance capability from a hardware perspective. I'm just bringing it up as an option because I know the EQ6/Atlas fits your requirements and your price tag.


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Patrick
Postmaster
*****

Reged: 05/16/03

Loc: Franklin, Ohio
Re: Celestron CGEM or Losmandy GM8? new [Re: Guillermo]
      #3644425 - 02/24/10 07:23 AM

Quote:

Celestron CGEM or Losmandy GM8?




Apples to oranges comparison really. The CGEM will carry more weight than the GM8, costs less, and has full goto capability. The Losmandy GM8 will have better out of the box PE on average (the tolerance range will be better controlled) than the CGEM.

There have been a number of hand controller issues with the CGEM mount, so that's a *BLEEP*-shoot, but I wouldn't let that stop you from going that route if all your other requirements are met.

Quote:

How does the Celestron CGEM perform for guided astrophotography. Any known issues?




The CGEM can perform very well for guided astrophotography. The All Star Polar Alignment routine is worth the price of admission alone. I cut 45 minutes out of my start up routine with ASPA on my CG5-GT mount.

Charlie mentioned the Atlas mount and it's also something you should consider, especially if you will always use a computer when imaging. I personally like the Celestron hand controller better than the Skyscan for those time when I don't want to hook up a computer, but YMMV.

Patrick


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CounterWeight
Postmaster
*****

Reged: 10/05/08

Loc: Palo alto, CA.
Re: Celestron CGEM or Losmandy GM8? new [Re: Patrick]
      #3644730 - 02/24/10 11:03 AM

If choice between Celestron (McMount) and anything else - go with anything else - Orion has a great return/exchange policy if things are wrong, fantastic responsive customer service and support - they are really out to please the customer.

I see Losmandy as a step up in quality and tinker friendly, sure there is a premium for it.

BTW - don't underestimate the importance of having a mount you CAN fudge and adjust vs. one that you touch and void the warranty or break something cheaply made. And yes I mean cheap vs. inexpensive. May not be important at first, but as things wear in and get use... 'stuff happens'.


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jrbarnett
Eyepiece Hooligan
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Reged: 02/28/06

Loc: Petaluma, CA
Re: Celestron CGEM or Losmandy GM8? new [Re: Guillermo]
      #3644811 - 02/24/10 11:36 AM

Neither. I'll explain.

I owned a GM-8 for about eight years. It's a nicely machined mount, but in my experience with a variety of different OTAs, not particularly stable with more than a 20# payload. I believe there are two culprits - the tripod-legs-to-tripod-head connection and the fact that the worm design is extremely prone to backlash creep.

I also have owned an Orion Atlas EQ-G for about three years. The Atlas is similar in some respects to the CGEM. The Atlas is a much more stable mount with a higher actual capacity than the GM-8. The fact that you get GOTO for the same price as the non-Gemini GM-8 is icing on the cake.

As for the CGEM, I truly prefer the Celestron NexStar firmware to the Orion's SynScan firmware (more stable, better features, etc.), but if you spend more than a few minutes scanning this forum you'll encounter dozens of CGEM gremlin reports. Given that the Atlas has bee around for longer than the CGEM, many of the bug have been worked out long ago. The CGEM is already a very good mount, and I suspect the CGEM will be a great mount in a year or two once Celestron gets a handle on the QC issues, but thus far I have held off in swapping my Atlas for a CGEM. I likely will do so at some point, but probably not until I see fewer negative reports for new CGEM mounts.

So I would choose an Atlas over either the CGEM or GM-8 were I buying today. OPT has the Orion Atlas for the same price as the CGEM ($1399) too.

Also, in addition to the Atlas I have two other GEMs, a CG5-GT and a CGE. I've never had a single problem with either Celestron mount. When I first purchased the CG5-GT, I dropped the mount head on my library floor and shattered the motor cover. I called Celestron support and asked to buy a replacement (since it was obviously my fault). They said "no" and insisted on sending replacement motor covers for both motors free of charge by express delivery. I was pretty impressed with their customer service on a relatively cheap mount. Maybe things have changed (as that was four years ago).

Regards,

Jim

Edited by jrbarnett (02/24/10 11:42 AM)


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tboconnor
member


Reged: 01/14/10

Re: Celestron CGEM or Losmandy GM8? new [Re: jrbarnett]
      #3646447 - 02/25/10 08:40 AM

The CGEM price is truely amazing in the States. In Australia the CGEM is almost double the price of the EQ6.

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AlexN
Pooh-Bah


Reged: 08/09/08

Loc: Brisbane - Australia
Re: Celestron CGEM or Losmandy GM8? new [Re: tboconnor]
      #3649832 - 02/26/10 10:27 PM

As is true of everything Celestron in Australia.. We get ripped off..

As for your choices.

I've owned
Skywatcher EQ6-Pro (Orion Atlas)
Skywatcher HEQ5-Pro (Orion Sirius)
Losmandy GM-8 (Non-Gemini version)

I found all three to be good thus far. The EQ-6 required a tune up to get best results, this voided the mounts warranty.
The HEQ5 is a bloody good little GEM since its warranty voiding tune up.. 30minute subs all night long with no subs thrown in the bin - no worries
The GM-8 is yet to see first light, but needless to say I've already stripped it down to have a look see at its internals.. Mechanically, it is superior to the Skywatcher mounts. The machining and level of quality cast the other two mounts into the shadows...

I'll be mounting the GM8 on a pier in my back yard, and the HEQ5 will be kept as a traveler..


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Luigi
Postmaster
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Reged: 07/03/07

Loc: MA
Re: Celestron CGEM or Losmandy GM8? [Re: AlexN]
      #3650339 - 02/27/10 08:23 AM

>>>I owned a GM-8 for about eight years. It's a nicely machined mount, but in my experience with a variety of different OTAs, not particularly stable with more than a 20# payload.<<<

I've never owned a GM-8 but had a G11 for 10+ years. When I downsized GEM mounted OTAs to </= 20 lbs, I wanted a lighter more portable mount and strongly considered the GM-8 but was discouraged from getting one by a well known dealer and denizen of these forums who put it in the same class as the CG5 as far as weight capacity goes. I got a CG5 instead and have been quite satisfied with it, a strong point being its tripod. Given this, I expect a CGEM would have significantly greater capacity than a GM-8.


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