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Losmandy G11 with Gemini

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#26 bseltzer

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Posted 23 August 2009 - 12:24 PM

Like Joselo, I had an Atlas for a while before got a G-11. The Atlas was a serviceable mount, but it quickly became a "hobby" in and of itself. Three months of tinkering, testing, and tinkering some more got it to an acceptable level of PE performance, but it still had its limits.

The G-11 beat the PE of my extensively tuned/modified Atlas by a very significant margin out of the box, and once I got past the Gemini learning curve, the mount has all but "disappeared" in terms of the attention I need to pay to it in any given session.

Like Joselo said, "Do it!"

-Bert

#27 Joselo

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Posted 23 August 2009 - 12:39 PM

Ohhh. yess.... The Gemini learning curve.....
It is steep, but once you learn it, you can align, slew, park with you eyes closed.

It is very intuitive....

#28 gnowellsct

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Posted 23 August 2009 - 03:07 PM

Like Joselo, I had an Atlas for a while before got a G-11. The Atlas was a serviceable mount, but it quickly became a "hobby" in and of itself. Three months of tinkering, testing, and tinkering some more got it to an acceptable level of PE performance, but it still had its limits.

The G-11 beat the PE of my extensively tuned/modified Atlas by a very significant margin out of the box, and once I got past the Gemini learning curve, the mount has all but "disappeared" in terms of the attention I need to pay to it in any given session.

Like Joselo said, "Do it!"

-Bert


What was the PE out of the box of your Atlas and G11, and what were they after you tweaked? Did you try the Ovision yet?

thanks Greg N

#29 bseltzer

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Posted 23 August 2009 - 07:54 PM

What was the PE out of the box of your Atlas and G11, and what were they after you tweaked? Did you try the Ovision yet?
thanks Greg N


After replacing ALL the RA and DEC bearings in the Atlas with SKF or Timpken high quality equivalents and the worm bearings with ABEC-5 ceramic equivalents and going to an Aeroquest worm and carefully optimizing the worm mesh, I got its PE down from 20" peak to peak to about 12" P-P.

By way of comparison, the G-11 out of the box produced a peak to peak PE of 7" (RMS ~0.97) measured with PemPRO. These measurements were repeatable over 3 separate sessions. I do have a bit of the dreaded 76 second "bump", but luckily its magnitude is low enough that it guides out pretty easily.

Since Ovision doesn't guarantee anything better than 5" P-P, I haven't felt the need to go that route yet. Right now, I running an image scale of 1.5" - 2.0" depending on which scope I'm using. I do have plans for a KAF-8300 based camera and a longer focal length scope, which would reduce the image scale considerably. If/When that happens, I may well consider the Ovision worm.

Meantime, I'm please with the results the stock mount is giving as seen here

NGC-7000

and here

M-27

Regards,
Bert

#30 gnowellsct

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Posted 23 August 2009 - 09:49 PM


What was the PE out of the box of your Atlas and G11, and what were they after you tweaked? Did you try the Ovision yet?
thanks Greg N


After replacing ALL the RA and DEC bearings in the Atlas with SKF or Timpken high quality equivalents and the worm bearings with ABEC-5 ceramic equivalents and going to an Aeroquest worm and carefully optimizing the worm mesh, I got its PE down from 20" peak to peak to about 12" P-P.

By way of comparison, the G-11 out of the box produced a peak to peak PE of 7" (RMS ~0.97) measured with PemPRO. These measurements were repeatable over 3 separate sessions. I do have a bit of the dreaded 76 second "bump", but luckily its magnitude is low enough that it guides out pretty easily.

Since Ovision doesn't guarantee anything better than 5" P-P, I haven't felt the need to go that route yet. Right now, I running an image scale of 1.5" - 2.0" depending on which scope I'm using. I do have plans for a KAF-8300 based camera and a longer focal length scope, which would reduce the image scale considerably. If/When that happens, I may well consider the Ovision worm.

Meantime, I'm please with the results the stock mount is giving as seen here

NGC-7000

and here

M-27

Regards,
Bert


Well if you want to keep up on Ovision results I recommend joining the Yahoo Losmandy group. Very hot topic there, much development, including pioneering work done by Floyd Blue who is known here.

Ovision considerably reduces peak to peak error and makes the worm adjustment a "reliable" procedure rather than a difficult game of cat and mouse. It also eliminates the a 76 second repeating error that happens, not always, but often and even usually, as a result of the worm bearings. The system becomes totally smooth and easy to guide.

regards
Greg N

#31 bseltzer

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Posted 24 August 2009 - 10:08 AM

Well if you want to keep up on Ovision results I recommend joining the Yahoo Losmandy group. Very hot topic there, much development, including pioneering work done by Floyd Blue who is known here.

Ovision considerably reduces peak to peak error and makes the worm adjustment a "reliable" procedure rather than a difficult game of cat and mouse. It also eliminates the a 76 second repeating error that happens, not always, but often and even usually, as a result of the worm bearings. The system becomes totally smooth and easy to guide.

regards
Greg N


Greg,

One of the first things I did after getting my G-11 was join the Y! Loasmandy group. It was also one of the best things I did, and I've followed Floyd's work on the mount closely. Not only has he done some great stuff, but he's tirelessly shared his experiences with others.

I'm sure the Ovision worm is a fine product, but the thing is, I'm still very much a beginner in AP. I've got a long way to go before my skills would justify investing in it, especially since I'm getting acceptable performance from the G-11 in it's box stock form.

And that's why, I'd still encourage the OP to take the plunge and get a G-11....

Regards
Bert






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