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LX-200 vs G-11 as an imaging mount

Started by mccarlp, 09/21/2002 04:13PM
Posted 09/21/2002 04:13PM Opening Post
Hi,

Hopefully this won't start a war between owners of the two, but I am trying to decide how best to upgrade my ccd and astrophotography setup. Leaving optics aside for a minute, I would really like some opinions about the LX-200 as a mount versus something like a g-11 with digital setting circles and dual axis motors.

I like the goto on the lx-200, but I realize all of the balance issues with a fork mount, expecially one with a refractor mounted on top. That was one of the things I had to fight with my c8. I do however like the idea of the eyepiece always being in roughly the same location with the fork. And for visual observing at star parties, the LX-200 can be slapped on a tripod in alt-az and be up and running in minutes with really good tracking.

On the other hand, an EQ mount is easy to balance, can carry any scope within its load rating, and is easier to setup polar alignment then a wedge. There are less electronics to go haywire in G11 setup than the LX-200 and my neighbors won't think I am running power tools at 2 a.m. Still, I hate having to rotate the tube all the time to reorient the eyepiece, and you still need a decent polar alignment for the mount to track well visually at star parties, etc. That means longer setup. And lets not forget the extra 30 lbs of counterweights you have to lug around. I have also read a few horror stories of G11's not living up to their reputation without a lot of tweaking.

My problem is that I want both for their advantages and neither for the disadvantages. I have been running this issue around in my head until I am getting dizzy and my wife is tired of "talking" about it.

So I am looking for advice. I would love to hear experiences from those who are actually using them to do photography or CCD work.

Thanks in advance,

Paul McCarl

P.S. I also know that there are better mounts, but I have a limited budget.

Posted 09/23/2002 04:21PM #1
hi,

I used a LX 200 8" scope for a couple of years and then switched to a GEM mount for imaging. At present I have a Losmandy GM 8 and a Mountain Instruments MI 250.

The LX 200 mount has it problems when it comes to ccd imaging because of the periodic error and some backlash problems. This can be overcome with the SBIG AO7 adapative optics device. The goto of the mount is as good as it gets and will put the object on the ccd chip most of the time. It will always be in a low power eyepiece.

The GEMs are better suited to ccd imaging. The G11 has a new worm gear which has improved its periodic error. I've seen plenty of fine images taken with these mounts. The dsc with the Losmandy mount is not as accurate as the goto on the LX 200.

The gm 8 is easy to set up ( about 10 mins ),you can polar align in about 2 minutes with the polar scope. The g11 being heavier takes a little more time.

The G11 has the advantage that you can use more the one OTA with the mount. The eyepiedc position is not a problem with SCTs and refractors. A newtonian will need rotating rings.

All in all I would get the Loamandy g11.


clear skies,

Larry

Posted 09/23/2002 06:27PM #2
Paul,

If you want to image, it's pretty simple. Get a GEM. The LX-200 mount is not really adequate for imaging--too much PEC (WAY too much), too much backlash, etc. An AO-7 does help, but now you've spent so much money that you might was well have bought a good GEM to start with--and learning how to use an AO-7 just adds another whole level of complexity.

It sounds like you are thinking of mostly visual work, though...you need to decide what you want to use the mount for most often. The alt-az LX-200 with Meade's packaged OTAs is a pretty good package for the price and for visual work, is hard to beat.

Jeff Hapeman

Jeff 8O
Posted 09/24/2002 10:39PM #3
Hi Paul,

Like you I was budget limited and the goto looked nice on the LX's. I also have a friend with a Losmandy G11. I thought my LX tracked better.

I owned an 10" LX200 for 3 years and used it for imaging extensively. I had the classic 10 as imo the 12" is way too heavy for the mount. They (12") are also more problematic in terms of image shift. The 8's and 10's can be effective as imagers stacking short exposures and if you are satisfied working with stacks of 2-3 minute images then the LX200 is excellent.Mine was and pointed incredibly well. For visual use and running down asteroids and photometric stuff the LX200's are incredible. The problem comes into play when one wants to guide these mounts for long high S/N CCD images. The main problem with them is not PE which can be dealt with quite effectively with the programmable smart drive but random gear errors which do not repeat on a periodic basis. These can swamp the best autoguider out there -I found if I could send it 1 to 2 corrections per second with an autoguider(seperate guide scope and camera) I could get decent results at f/6.3 using 5 to 8 minute exposures. Going longer than this might result in flexure killing ~1/3 of the images. I also soon discovered that most of the time seeing conditions wouldn't allow imaging at long focal lengths and was forced to use telecompressors nearly all the time.

I got tired of this and discovered the joys of small Tak apos and sold the LX200 when finances allowed the purchase of an AP1200. Do I miss it?-nah ...


If I were in the same circumstances again I would probably purchase another one though I could only recommend the LX200 if you were aware of what you are getting into. It can work but you would probably be better off with a good GEM unless you like to tinker half the night instead of image. The G-11 is alot like the LX200 with some TLC they can be great or they can be marginal.

Have you considered a used small Tak mount and a Mak or Schmidt newt? For the bucks you want to spend they would be viable options too.

Mike
Posted 09/25/2002 01:35PM #4
It would also depend on what you want to put on that G-11 mount. WIth the right scope, a G-11 could be very nice. And it's upgradable to GOTO without too much fuss. The newer G-11s have a new (and better) process for making the worm and gear, and are better suited for photography than the originals.

Ron Wodaski
author of "The New CCD Astronomy"
http://www.newastro.com

Ron Wodaski
New Astronomy Press
http://www.newastro.com