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Hey Steve,

From my experience and thanks to Brian's help I have learned that you shouldn't worry about DEC backlash measurement.
It is just a thing PHD2 can't handle with a spring loaded version. Besides latest version of PHD2 will measure and compensate it while guiding, the more you guide the better it gets.
Also the better your polar alignment and seeing conditions are, the less it has to correct DEC.

Your RMS error looks good!

Cheers,
Carl

I received my new GM811G and finally got out under the stars to start learning the mount and Gemini 2 system.? Before I got started, I noticed some movement in the DEC axis.? With minimum effort, i can wiggle the saddle, i.e. DEC axis.? I am working with PHD2 and got some messages about the DEC axis, don't remember exactly.? I ran the guiding assistant and I thought the numbers looked good, except for the DEC Backlash was highlighted.? Here are some of the values:

RA Peak? 0.44px(6.73arc-sec)
DEC Peak? 0.37px(5.61arc-sec)
RA Peak to Peak0.47px(7.13arc-sec)
RA Drift Rate-0.09px/min(-1.41arc-sec/min)
RA Max Drift Rate0.04px/sec(0.67arc-sec/sec)
Drift-limiting exposure2.4s
DEC Drift Rate -0.01px/min(-0.21arc-sec/min
DEC Backlash >=34970 +/-99ms(247.1 +/-0.7a....
Polar Alignment Error 0.9 arc-min

High-frequency Star Motion
RA, RMS 0.05px(0.80 arc-sec)
DEC, RMS 0.05px(0.75arc-sec)
Total, RMS? 0.07px(1.10arc-sec)

Should I address the looseness in the DEC axis?? I've watched the video how to adjust the spring-loaded worm gear.? Would that be the way to eliminate the looseness?

Thanks for any help, Steve

On Tue, Apr 21, 2020 at 07:50 PM, <esmdavis1@...> wrote:

Have you measured your PA?

I believe from memory, having read something on PemPro forum a few weeks ago, that Brian has a sub 1 arc sec PA error using PEC (with Gemini obviously) and below 3" without PEC. But I believe that is with latest spring loaded worm gear G11.
I think that with proper seasonal worm gear mesh tuning you should be able to reach 5-7", which should allow unguided photography well over 50mm focal length.
Now if you are using a photo lens, from my experience, you'll get additional optical aberrations which might make it look like mechanical issue, were in fact it is an optical issue. That is especially true for blue/green channels.

On Wed, Apr 15, 2020 at 05:35 PM, Brendan Smith wrote:

sadly even the shipping to down under is a stretch! ?

Huh, I live in Switzerland, I might be able to help with lowering shipping cost...

Thanks, Brian, I sent you a PM. It is unrelated to Losmandy but related to other astrophotography equipment that you have some specific experience with.

Was out last night for a few hours.? Tracking and pointing were good.? I double checked and yes, once again Sirius was well above the horizon but missing from the Bright Star list after a while.

I'm still getting used to and learning the Gemini 2, and was wondering if it's possible to look for an object by name like I could with the Celeston NexStar hand control, which had a list called "Named Objects"?? For example, if I did not know the Messier number 42 for the Orion nebula, could I just look up "Orion nebula" somehow?? Or do I have to know the catalog number for every object?? Not a big deal, just a convenience.

Thanks again for any help.

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Hi Brian,

I was reading some of your posts on CN on flats issues you were having. Can I contact you by PM to discuss further?? I don't know how to do that from this forum.

Well, I answered my own question last night. As recommended in the G11 manual, I calibrated my autoguider at a speed of 2x, then guides at a speed of .5x. As I suspected, the results were a disaster. I then recalibrated and guided at 2X, then again at .5x. Unlike my previous experience guiding was much more accurate at .5x. I guess I could have saved my time and just followed the other members recommendations. So as to not have wasted the whole night, I finished up by taking a tour of open clusters in Canis Major.

Wow, that is quite impressive. My g11 couldn't do that. Have you measured your PA? Mine is 25 to 35 arc sec. I have an older non Gemini mount. It does do an adequate job with the auto guider, but would.t dream of doing un guided photography with anything more than a 50 mm lens.

Cheers Clif. ??

best setting for goto or slew speed is 500-600X. ?This is because motors have sweet spots in speeds and efficiency and 800x is a little harsh on them. Running them slightly slower won’t really effect using the system but will extend the motor life as you’re stressing them less. ? Yes goto slews only last a few seconds but it’s a huge stress on them. ?I recently read heat is one of the biggest killer of these DC motors....including what they previously mentioned ? ?Slower slewing keeps the heat lower ?

The new motors are much better and should last longer than the old. ?Since the old lasted ~15+ yrs. ? Winning!
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Brendan

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My new high torque servomotor just arrived.? I installed it on the RA gearbox and moved the original Dec motor (not high torque) back to the Dec axis.? Original RA motor goes in junk box.? Both motors now run fine at a setting of 300 and 700.? Have not tried 800 yet.? The new values for RA lag and duty are 3 and -4 and the values for Dec are -1 and 1.? The values for RA with the old motor were -11 and 15.? I got no stalls or alarms.? So far, so good.

Thanks for all the help...

????????? Clif

PS, Venus sets below my roof well before Sirius hits the horizon.? When Venus was in the Pleiades recently, I had to hightail it with setup and camera and all to capture a few shots of that grouping before Venus "set."

LOL, GN.? That is a reasonable possibility, 'cept I've been into astronomy for almost 6 decades now, so I know what's Venus and what's Sirius.? Trahhhst me!

Hi Sonny and thanks for the welcome!

Now that you jogged my memory, I think there was a G811 setting and that's the one I chose.? I had thought about doing the factory reset; maybe I'll go ahead and do that.? With the virus shut-in situation, I'm running out of projects anyhow.? And we finally have some good nights coming up, albeit with iffy seeing, but great transparency and I want to shoot DSOs, so that's welcome news.

I've watched all of the Losmandy videos, and they've been a GREAT help.? Much as I liked the Celestron CGX, helpful tutorials were definitely lacking there, as was the operating manual.? But that's not to "dis" Celestron stuff.? I liked the mount, and love the EdgeHD SCTs!? Have owned a couple of those.? Anyhow, back to Losmandy...

I have to drag my outfit in and out the back door too - just a regular opening, and I have it on JMI Wheeley Bars, too.? So, it's "counterweight out first" then maneuver the other two struts around the door jambs.? Getting it all back in is quite a bit more hassle than getting it out, that's for sure.

Hi Brian,

Thank you for the response.? I did not realize I had responses here as I was under the impression some notification would come into my mailbox.? Just checked here on a hunch.? So thanks to everyone who did respond.? I'm likin' this already!

I have checked and rechecked (and rechecked) date, time and location, and all's well with those (and the battery, btw).? I'm using UTC for the time.? I've not tried Stellarium yet.? Still learning the ropes with a new mount and configuring PHD guiding, ASCOM, and Astrphotography Tool.? For this old dog, that's alotta new tricks all at once.? Last night we were out (we being my wife, who assists me with PoleMaster alignment and some of the tech stuff on the computer when needed, and crawls into her Snoopy "I Need My Space" sleeping bag that we got from Lands End and watches for meteors) and could not get the mount to connect to the computer.? She finally figured out that some cleaning up she'd done the other day apparently removed the Gemini 2 setup parameters, so she did a system restore and that fixed it.? Just making a note of that here, in case anyone else encounters that problem.

As for "astroitalian," I'm of Italian descent, and lived in Italy a number of years.? Had an astro pal there whom I went to visit once, and did a Messier Marathon with a bunch of other Italian astrophiles.? Great time!