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Mark,

That's some really nice photography and you obviously know your way around a telescope. You've been using a Gemini for a while so you must know the ins and outs.

My first though is that a many-stars model could have some erroneous entries. If I synch on the wrong star the whole point accuracy will drop, so best to do a Cold Start and begin again. I now use only one or two stars for align and synchronize and that seems to work for me. But I am only imaging and use solve and center in SGPro to get on target. But in most cases a good model will get me pretty close and will most likely at least be in the finder scope.

Then the usual suggestions will be to check for the correct time including DST and location, or check the coin battery in the G2 unit.


Good luck,

John




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_____________________________________________________________________________________________________________________________________________________________________________

Losmandy G11G2 on pier; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, Sequence Generator Pro and PixInsight user

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I hate to say this but I agree with the Op.? I've been trying for 2 or more years to get my G11 to do accurate gotos as did my old celestron right out of the box.? And the celestron had to be carried out and realigned every night whereas the Losmandy is fixed in a skypod and stays put.? Polar alignment is as good as it gets.? I am so frustrated I hardly use it anymore. :(??
But I do have an actual question which is, where to get and how to use a plate solver?? Maybe that will help.??

Hi George,
To answer your first question, where to get a plate solver, I suggest

The program in question is called ASTAP. I use it with NINA imaging software, as well as Stellarium, Phd2, and of course Gemini.
The how is a little more involved. The quick answer is that that ASTAP solves the RA and DEC for the image you give it, basically like

Then, other software, NINA in my case, uses that information to move the scope, take another image, solve that image, move scope (repeat as necessary) until the plate solved RA and DEC are within limits you have set (in NINA in my case).
If you're not imaging, of course, plate solving isn't going to work, as far as I know. Well, you could put a camera on the scope, use plate solving to get the object centered, remove the camera and substitute an eyepiece. Your post didn't say if you were an imager.
I hope that gives you some ideas. Perhaps someone else here can give you more ideas of how to do what you want to do.
Ken

On Wed, Aug 3, 2022 at 08:24 PM, Mark de Regt wrote:

Hi,

?

I am primarily an imager, imaging remotely.

?

But I like to look through a scope from time to time, to renew old acquaintances.

?

I started out my serious astronomy addiction many, many years ago with the original Meade LX200.? I loved it.

?

I especially loved how quick and easy it was to do a simple 2-star alignment, after which goto was dead on.

?

But I got too old to comfortably lug the unwieldy mount/OTA assembly up to the tripod.

?

So, eight years ago, I got a G11 (with Gemini 2), on which I mount a C11 EdgeHD.?

?

But I have never liked either the cumbersome job of doing a multi-star alignment (once it’s polar aligned), or the relatively poor pointing accuracy after that (not even on the eyepiece with frustrating frequency).? So I find that I never, ever go out anymore.

?

Before looking for alternatives, I’m curious if anyone has some wisdom to offer on what I may be missing.

?

To forestall thoughts that it’s all user error, it’s not.? The polar alignment is very easy, quick and accurate with PoleMaster.? And I then do the multi-star alignment using an illuminated-reticle eyepiece.? I am careful with the centering.? And I use many, many stars.? But it makes no difference—the pointing is just not very good.

?

Thanks for any help!

?

Mark de Regt

http://www.de-regt.com/Astronomy

Hi Mark,

I will echo what others here have already said, very nice imaging work!?

As to your G11 appearing to not performing accurate GOTOs start with the basics.

-Verify your Gemini 2 has a new battery from a name brand maker from a known good supplier
-Verify your Gemini 2 has the latest production released Firmware and hand controller here:? ?
-Once above is completed do a factory reset using RESET HGM DEFAULTS to flush potentially erroneous data inadvertently stored in microcontroller?
-Do a Warm Start manually reconfigure all Gemini 2 information, if possible use the Gemini 2 Web interface for more options?
-Consider installing new servo motor cables they are often a source of intermittent and hidden issues related to position on older mounts
-Mount may need cleaning depending on the conditions it was used and stored in?
-Check that clutch discs are clean and DRY very important to eliminate any unintentional movement??
-Set worm backlash, confirm the bottom socket headed cap screws are snug?
-Check that all of the set screws in the Oldham couplers are present and snug?
-Check for worn Oldham coupler sliding-plastic center connector piece?
-Check for loose or missing mounting hardware and standoffs used to attach gearboxes?
-Check for loose or missing mounting hardware and standoffs used to servo motors?
-Check gearboxes for excessive backlash or that are hard to turn, replace if in doubt??
-Check that the gearbox backs are solidly attached to the gear box body, replace if in doubt?
-Add plastic gear compatible lube and carefully set servo motor gear mesh for minimal noise?
-Check?worm axial end play, if the worm has any perceived movement between the worm bearing blocks adjust it out?

Alternately replace classic Losmandy 2-piece worm blocks with new gen II OPW (one piece worm blocks). The newer OPWs are superior in every important way but mostly for the stronger more accurate bearing blocks locked into virtually perfect worm bearing alignment which allows getting worm backlash just right much easier. This will be especially helpful if you set backlash in the dark after mount cool down which is how you can get the minimum backlash possible on an unsprung worm mount and classic straight line drivetrain.?

It is surprising how often people set their GPS location and time data incorrectly. You can completely avoid this issue this by using and setting the Gemini 2 clock to UTC time with zero local offset and go to the Gemini-2 website Lat-Lon-UTC page and get the correct data in the correct format for your Gemini-2 controller. Use this link if you don't know what I am talking about:

Side note: my standard Gemini 2 setup uses 2 stars on the East side and 2 stars on the West side of the pier combined with an occasional SYNC command as the night goes on if GOTO quality deteriorates or stuff gets bumped in the dark, it is not unusual to need to Sync location once in a while. My mount GOTOs are virtually always perfect. That said a 2-star model seems to work just fine too but split the alignment stars on either side of the pier.?

Sorry for all the revisions and reposts, I want to get this as close to right as I can, this is often a sore subject for some Gemini 2 users who often came from other GOTO systems. Stick with the program and you will see it works very well.?Yes, Gemini is different but in a good way.?

I hope this helps!

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?

On Thu, Aug 4, 2022 at 12:03 PM, George Anderson wrote:

I hate to say this but I agree with the Op.? I've been trying for 2 or more years to get my G11 to do accurate gotos as did my old celestron right out of the box.? And the celestron had to be carried out and realigned every night whereas the Losmandy is fixed in a skypod and stays put.? Polar alignment is as good as it gets.? I am so frustrated I hardly use it anymore. :(??
But I do have an actual question which is, where to get and how to use a plate solver?? Maybe that will help.??

I'm sorry to hear you have not been successful for so long in getting your Losmandy G11 mount to work like a Celestron mount. The Celestron controller and Losmandy Gemini 2 controllers are very different animals. You will need to let go of your old notions from the Celestron and learn something different in order to get the Gemini 2 controller to work. I came from the EQMOD mounts from Orion and SkyWatcher and it didn't seem to be that hard to figure out.?Most people figure it out, soon enough it is not that difficult but if you just stick with it to get an understanding of how the Gemini 2 works you will be rewarded with an excellent mount and controller.?

IDK where you are located but my best advice is to make some friends in the local astronomy club and have them over some night to help you figure out how to use your Losmandy mount and Gemini 2 computer. If you are lucky maybe there is someone in the club with a Losmandy mount and Gemini 2 who would be willing to teach you how to use the Gemini 2.? Also IME it is a lot more fun observing visually with other folks so you can share eyepieces and gain experience with different gear.?

Hope this helps.?

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?

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Mark,

What kind of finder scope are you using, and do you know the FOV??

On my C925EdgeHD, I have a Telrad base that I use to pop that on when I first start with a new star model. If the first star is not in the FOV of my Zenithstar61 with an ASI290Mini, it will be visible in the Telrad at unity. After I sync on the first star, I can remove the Telrad and further stars or objects will then be in the guide scope's FOV as seen in PHD2.

If you are not even getting into your finder scope, Chip's checklist should help get you there. Some type of unity finder is always a good fallback.

John

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_____________________________________________________________________________________________________________________________________________________________________________

Losmandy G11G2 on pier; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, Sequence Generator Pro and PixInsight user

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On Thu, Aug 4, 2022 at 08:18 PM, Mark de Regt wrote:

Thanks for the responses!

?

I have changed the battery a couple of times; it makes no difference. The goto just sucks.

Specifically, using a 25mm eyepiece on my scope (a bit over 100x), the object almost never is centered, and, with disconcerting frequency, is not even on the FOV (especially with a higher-power eyepiece).

I am VERY careful only to accept alignment stars that cannot be confused.? I have an excellent finder on the scope, so I typically can coax the correct star to be centered.

?

But I got an expensive goto mount because I don’t want to spend more time looking for things than looking at things. And at my latitude (47.7 north), it’s late in evening when it’s dark enough to even start the process in the summer.? I find little attraction in spending a great deal of time polar aligning (and this on a tripod/mount that never moves, BTW), then getting a model set up, then having to search in the finder for the actual object I’m expecting to be on the eyepiece.

?

Being an inveterate imager, I obviously am familiar with the concept of a plate solve.? And I certainly do a TPoint run with my imaging system from time to time.? But I do not understand how using plate-solving will transform this from a long, tedious, and ultimately unsatisfactory process into one that has me viewing in 15 minutes, with objects always in the eyepiece.

?

Thanks again for any additional hints you can give!

?

Mark de Regt

http://www.de-regt.com/Astronomy

?

From: [email protected] <[email protected]> On Behalf Of Mark de Regt via groups.io
Sent: Wednesday, August 3, 2022 8:24 PM
To: [email protected]
Subject: [Losmandy_users_io] Usability Question

?

Hi,

?

I am primarily an imager, imaging remotely.

?

But I like to look through a scope from time to time, to renew old acquaintances.

?

I started out my serious astronomy addiction many, many years ago with the original Meade LX200.? I loved it.

?

I especially loved how quick and easy it was to do a simple 2-star alignment, after which goto was dead on.

?

But I got too old to comfortably lug the unwieldy mount/OTA assembly up to the tripod.

?

So, eight years ago, I got a G11 (with Gemini 2), on which I mount a C11 EdgeHD.?

?

But I have never liked either the cumbersome job of doing a multi-star alignment (once it’s polar aligned), or the relatively poor pointing accuracy after that (not even on the eyepiece with frustrating frequency).? So I find that I never, ever go out anymore.

?

Before looking for alternatives, I’m curious if anyone has some wisdom to offer on what I may be missing.

?

To forestall thoughts that it’s all user error, it’s not.? The polar alignment is very easy, quick and accurate with PoleMaster.? And I then do the multi-star alignment using an illuminated-reticle eyepiece.? I am careful with the centering.? And I use many, many stars.? But it makes no difference—the pointing is just not very good.

?

Thanks for any help!

?

Mark de Regt

?

Hi Mark,

This is a hobby where you often need to do things for yourself, especially if you are not in or near a good sized city. If your mount has never been able to do accurate GOTOs and in nine years you have not managed to resolve the issue it seems to me you need something more than just a battery change.?

What if anything mechanically have you done to the mount to resolve this issue?? Other than changing the battery of course.

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?

I've had similar experience with my pier mounted Celestron fork mount on a wedge at F10 or at F7(with Focal reducer) . The GOTO's were seldom in view in my camera, I could see them in the guide scope, but seldom bothered. I would plate solve in NINA and go for there. I never do visual anymore, so it really didn't bother me much. My polar alignment was close but not spot on, and forums indicated that if I was guiding, being close was close enough.

Recently, while trying to solve another issue (poor tracking with oval stars) and after a 3hr afternoon nap. I spent an almost an entire night, with PHD2 drift alignment (the gold standard on polar alignment) refining my polar alignment and got it very, very close to as good as I can with a cheap fork mount(less than 1 arc min total). I checked south, then West, then South again, then West until I could not improve on it anymore. I was amazed when I went for a GOTO on my first few objects and they were nearly perfectly centered in my 33 x 32 arc/min view. it has been cloudy or i have been out of town since then, and haven't got many hours on the new polar alignment but I feel that night I spent working on drift alignment was well worth it.?

?It may be worth it to try Drift aligning your mount with PHD2, especially if you're doing visual without the aid of guiding.

Mark,

You have done the first thing on my list. That didn't work so if you just keep chipping away going top to bottom you will eventually nail the issue.

One of the easiest things is to do a factory reset to HGM default settings. The small controller in the Gemini over time can accumulate small errors in the processor's non-volatile data store. These errors may also be propagated to the configuration files and reloaded inadvertently. So my advice is to reset the Gemini to HGM defaults and then manually enter all the configuration and setup data. Then overwrite the old data files by saving the new configuration files after fresh manual configuration.?If this doesn't work you have to get mechanical.?

It seems like you have avoided going mechanical for eight years so you probably are not particularly comfortable doing this work and should likely seek help.?

The specific problem area to look into is the drive system and the way power is transmitted to the worms and worm gears. When you have a Losmandy mount that behaves mostly okay but only gets close to the target object when commanded to performs a GOTO this is often where the issues lay. The small power coupler connections, some extra endplay and backlash is all it takes to keep the scope just off target. With a C11's narrow FOV it doesn't take much mechanical slack to miss a GOTO target.?

I think you should be able to find a mechanically confident Losmandy owner in the Seattle area to come out to look at your mount and help you sort out the issue. Give the local astro clubs a try or appeal to the Losmandy users here and in the Gemini-2 group.

There is probably someone within a reasonable distance who would be willing to come and help. Offer to buy the pizza and beer and I am certain you would have a few people come out of the wood work.?

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?

On Fri, Aug 5, 2022 at 08:51 AM, aughtago wrote:

I've had similar experience with my pier mounted Celestron fork mount on a wedge at F10 or at F7(with Focal reducer) . The GOTO's were seldom in view in my camera, I could see them in the guide scope, but seldom bothered. I would plate solve in NINA and go for there. I never do visual anymore, so it really didn't bother me much. My polar alignment was close but not spot on, and forums indicated that if I was guiding, being close was close enough.

Recently, while trying to solve another issue (poor tracking with oval stars) and after a 3hr afternoon nap. I spent an almost an entire night, with PHD2 drift alignment (the gold standard on polar alignment) refining my polar alignment and got it very, very close to as good as I can with a cheap fork mount(less than 1 arc min total). I checked south, then West, then South again, then West until I could not improve on it anymore. I was amazed when I went for a GOTO on my first few objects and they were nearly perfectly centered in my 33 x 32 arc/min view. it has been cloudy or i have been out of town since then, and haven't got many hours on the new polar alignment but I feel that night I spent working on drift alignment was well worth it.?

?It may be worth it to try Drift aligning your mount with PHD2, especially if you're doing visual without the aid of guiding.

The OP uses a PoleMaster which in my experience is one of the most accurate automated means of doing PA. I routinely am under 30 arcseconds using the PoleMaster after a second iteration.?

After mechanical issues with the mount the last item to consider is the way his C11 is mounted. Celestron supplies a crappy orange extruded dovetail which tends to crack along the area where the saddle clamp compresses the dovetails. It happened to me twice on my own C11 and C14 scopes and I have discovered the same problem with other orange C11 and C14 dovetails while servicing other people's OTAs and replaced them with Losmandy sources dovetails. The older heavier black machined Celestron dovetails don't seem to have this issue, at least not so far.?

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?

On Fri, Aug 5, 2022 at 12:24 PM, Chip Louie wrote:

Mark,

You have done the first thing on my list. That didn't work so if you just keep chipping away going top to bottom you will eventually nail the issue.

One of the easiest things is to do a factory reset to HGM default settings. The small controller in the Gemini over time can accumulate small errors in the processor's non-volatile data store. These errors may also be propagated to the configuration files and reloaded inadvertently. So my advice is to reset the Gemini to HGM defaults and then manually enter all the configuration and setup data. Then overwrite the old data files by saving the new configuration files after fresh manual configuration.?If this doesn't work you have to get mechanical.?

It seems like you have avoided going mechanical for eight years so you probably are not particularly comfortable doing this work and should likely seek help.?

The specific problem area to look into is the drive system and the way power is transmitted to the worms and worm gears. When you have a Losmandy mount that behaves mostly okay but only gets close to the target object when commanded to performs a GOTO this is often where the issues lay. The small power coupler connections, some extra endplay and backlash is all it takes to keep the scope just off target. With a C11's narrow FOV it doesn't take much mechanical slack to miss a GOTO target.?

---
I have a Losmandy Titan with a C-14 EdgeHD & after a mechanical overhaul of the mount, I had real issues with accurate GOTOs. Sometimes GOTOs would be spot on, but most of the time, whatever I was looking for was on one side of the field of view or the other or completely out of the fov. As it turned out, backlash in declination was my issue. One of my brothers remarked that when he reached for the focuser one night, the object I had centered went completely out of the fov! That must have set off a lightbulb for me, because I grabbed the scope, nudged it in declination & found I could move whatever was centered in & out of the eyepiece fov (22mm Nagler). How I missed this when I reassembled the mount, I haven't a clue but after working on removing the declination backlash, GOTOs have been spot on.

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Mark,

Would have to agree with Chip on all the major points. You might need a nearby Losmandy user to help diagnose what you are seeing. If they confirm your routine is sound, there might be mechanical issues that must be addressed to get the performance you want. If there is no repair person close by, then a service trip back to the factory seems in order.?

Personally, I haven't used any GoTo of any brand that always lands perfectly on every target anywhere in the entire sky. There is always some error with gearing or optics flop from far east to far west that won't take you everywhere all the time. Synching on a bright star in the general vicinity of your intended target should take you most of the way there. Meade used to use High Precision Pointing in their LX200's I had 20 years ago, where you would synch on 3 stars near a target, and then the GoTo would be right on. Hopefully this operation shouldn't be necessary with modern mounts.?

You should have enough of an action plan with the feedback given. If you implement what has been suggested, you should be as tuned in as you can get. If you want a different performance level yet, you should be able to sell your Losmandy quickly on Cloudy Nights, and then try a $10-20K brand with the latest encoder and computer technology available.

Hope you find the solution you are seeking.

Regards,

John
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_____________________________________________________________________________________________________________________________________________________________________________

Losmandy G11G2 on pier; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, Sequence Generator Pro and PixInsight user