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From LX200 with wedge to Atlas...

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#1 Stilletto

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Posted 20 January 2011 - 11:41 PM

If I can't get the tracking straight this tear down I am going to switch to an Atlas EQ-G. The question I have is this:
I currently have a 10"LX200 with a superwedge on a pier.
Has anybody converted to a GEM from this setup?
I am concerned about height, or rather keeping the general height the same. Right now the telescope is at the perfect height, and I would like to retain this orientation IF possible, although I know that the geometry of a GEM is going to change things up a little....
Any guesses as to how far up I will have to go with it to keep similar orientation?

#2 jrcrilly

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Posted 20 January 2011 - 11:53 PM

If I can't get the tracking straight this tear down I am going to switch to an Atlas EQ-G. The question I have is this:
I currently have a 10"LX200 with a superwedge on a pier.
Has anybody converted to a GEM from this setup?


Switching to a GEM may be an answer for you; at your low latitude a wedge can be problematic in terms of fork arm flexure. However, switching to a GEM with worse tracking than the mount you currently have is likely to bring on a whole new set of issues. I'd avoid a GEM unless you can get something in the same performance class as your forkmount.

#3 Stilletto

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Posted 21 January 2011 - 12:02 AM

John, do you think that the LX200 Classic > Atlas performance wise? (in general...mine is plagued with skips and jumps and the like and I have spent over a year on it so far :D)

#4 Nils_Lars

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Posted 21 January 2011 - 02:10 AM

I think there about the same as long as the Atlas isnt over loaded it works well.

#5 imjeffp

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Posted 21 January 2011 - 05:20 PM

Skips & jumps aren't normal for the Classic. Are you sure the pots are set correctly?

A GEM isn't going to fix the inherent problem of imaging with a scope with a moving mirror.

And to answer the original question, I moved from the 10" Classic to a LXD 650 on my pier with no clearance issues, but it sure does put the end of the scope in different places.

#6 Stilletto

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Posted 21 January 2011 - 09:03 PM

Yep, the pots are dead on. I do have slop in the RA axis which I am taking care of on this tear down. Every 2 or 3 seconds I get a multi arc sec jump to the east or west. I am out of patience and going to move on if this fix doesn't work.

I assume you had to re-do your pier plate etc...
I am worried if I just plop the GEM on the pier plate that the OTA will be too low.

#7 Gargoyle

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Posted 21 January 2011 - 09:10 PM

Paul,

I ran an 10" LX200R - Milburn Wedge on a pier for close to two years. Over that time I tried everything to obtain some level of respectable tracking to no avail. We're talking about hundreds of hours here. The upside to this was that I learned a lot about the LX200 mount, wedges, balancing and PEmpro. The downside was of course I could never track unguided for any reasonable length of time and additionally could not obtain consistant successful autoguiding calibration on a night to night basis. This was quite frustrating for me as I belive (and have observed) that wedge mounted fork based configurations can and do provide high quality tracking systems. I still believe this even now. I believe also that there may have been mechanical issues across the mount, wedge, motors and even the pier that just would not allow for proper alignment. As to exactly what caused my inability to obtaing good traincking alignment, who knows? But I personally could not get it done.

I obtained a used MI-250, de-forked the OTA and within two weeks had 3 minute unguided tracking. I'm now a GEM fan. So for me, the exercise was a success. But here's some thoughts. A GEM mount may not solve all of your problems and in fact, it may increase them. There's a learning curve with GEM's (as with any mount) and limitations too (meridian flip for example), and as John stated above, there's no gain in using a GEM with load-tracking capbility that's less than your current LX200 mount. That is the most important aspect of selecting a GEM.

So for example, my setup when rigged for astrophotography comes in close to 40 lbs. Following the 50% rule, that means the mount should be able to manage 80 lbs. The Atlas EQ-G is rated for 40 lbs. So if your not doing astrophotography, you'll probably be OK with the 10" LX200
(OTA weight of about 27 lbs - I think this is correct), plus accessories, etc.. If your are planning on Astrophotography, you may want to think about a mount that can manage a higher weight load.

Going to a GEM is certainly doable. But beware of the load limits.

Best of luck to you!

Jerry

#8 imjeffp

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Posted 22 January 2011 - 01:21 PM

I assume you had to re-do your pier plate etc...
I am worried if I just plop the GEM on the pier plate that the OTA will be too low.


Nope, just made a small adapter, and plopped the gem on the plate. The scope height is very similar.

#9 Stilletto

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Posted 22 January 2011 - 02:45 PM

Jerry,
Thanks for the advice. I am hoping that being permanently mounted on a pier and in a dome that I can push that AP weight limit a little bit....the 10" is the biggest scope I will be using, most are smaller.

Jeff,
Thanks. I was hoping it would be close. I will probably get a better Idea when I get a GEM in my hands, as I have never owned one before :crazy:
P.S. I am going to check the pots again this tear down just for you :grin:






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