LOSMANDY GEMINI 2 GOTO SYSTEM

Chris,

I think there is some user error here. Let me guide you through the steps.

1) Before power on, make sure the mount is physically set up with the counter weight down and pointing straight ahead. The more accurately you do this to start with, the easier the later steps will become.

2) Power on mount and once all powered up, set up location coordinates, time zone and time and date. exact instructions are on the gemini II site, I'm out of country so cant refer to my mount now.

3) Make sure the mount is set up to ask you which start up mount you want. If the is is a set up that you set up and tear down every night just let it default to cold start. I like the setting that says ask if possible.

4) Restart mount in cold start mode. It should ask you if you want to model. If you dont get this screen then you are using very old firmware. Please update firmware.

5) Build model. It should work more easily now.

It's hard to hold my tongue in this thread. I have used Gemini 2 likely as much as anyone although I have not used its full set of features.
I have owned, and used for AP, the G11 Gemini 2 since early 2011. Back then the FW was very rudimentary and there was cause for disappointment, yea, even consternation, among users who had no idea just how incomplete the software was when they purchased.

All that changed by the early summer of 2011. Since that time, Gemini 2 has been eminently useable and has improved, albeit in fits and starts, since then.

I don't get the complaints voiced here. My GOTOs are just fine and I rarely bother with more than 2-3 stars on one side of the meridian and NONE on the other! When it comes time to flip, I add 1-2 stars on the other side and, certainly at FLs up to 600mm or so, I have no trouble finding my target. And I don't model build often either, even if I have moved the mount. A simple synch seems to work just fine. My problem in model building is lack of stars due to trees, not Gemini 2.

Runaway slews? I never had one that was not attributable to the sticky soft key "feature" that I hated. Provision was made some time ago to lock that feature out and I have not had a runaway slew since.

The biggest problem I see with Gemini 2 is the lack of a manual. It is a wonderfully complete system and has more features than most of us will ever use. But it is tough to figure all those features out with no manual.

That new bugs pop up with new FW releases is not surprising. I am not sure Gemini 2 will EVER be truly "finished." It will continue to evolve until it is supplanted by Gemini 3 at some time in the future. I hardly see this as a bad thing. I have had no reason to update my FW since last summer. So, I'll allow some things may have "run amok" since that time.

But, I have to wonder at the discontent expressed here.


I have seen hardly any of the problems people are reporting here!

The biggest problem I see with Gemini 2 is the lack of a manual. It is a wonderfully complete system and has more features than most of us will ever use. But it is tough to figure all those features out with no manual.

Yes, yes, yes, a thousand times yes.

I've had my GM-8 since last March and it worked flawlessly for me until recently when it started stuttering while slewing in RA. I traced it to the gearbox and when I removed it, the box was apart slightly, causing problems with the motor shaft gear engaging correctly with the one in the gearbox. It snapped back together but I'd already talked to Scott Losmandy and he'd told me to return it for replacement. Last Tuesday, Jan 29, I sent it off and got the replacement yesterday, Feb 6. It was delivered to them on Friday so they must have sent the replacement out immediately.
I installed it last night but it was cloudy. When I got up this morning it was clear so I did a polar alignment with the scope and slewed to Vega which was just off center in my 20mm eyepiece. The same with Altair. Arcturus wasn't as close to the center but still was very good. I did not build a model, just synchronized on each of them. I did experience the runaway slew problem, which is an annoyance.
I purchased this mount because it is quality, easy to work on if necessary and parts are readily available. It took a couple of days for Scott Losmandy to get back with me, but he did call me which I thought was very good. Replacing the gearbox was super simple too.
I understand that people have issues with gear at times It happens. But I also think these mounts are a heck of a deal and as the owner of a Synta mount too, there really is no comparison.

Edit: Before this problem I was getting great 20 minute subs.I haven't tried anything longer yet.

Terry
The runaway slews---
Have you tuned off the sticky key feature?

Hi Terry. No...how do you do that? I'll do it right away!

Is it true that if you use a good third party PC based guiding software, for example SkyX, none of these problems manifest themselves?

Bart, I spent all last night guiding via PHD over ASCOM and had no issues. Mind you, it's a small sample. I think I'll lock on the back buttons too.

Terry, thanks for your take on everything. I agree that we're probably being overly harsh on the G2 and that much of it is probably user error at this point.

Hilmi, thanks for the walk through bro . Very helpful!

Obligatory picture:


Not bad for a first light!

Hi Terry D.
You stated your using fl up to 600mm. There's a big difference when your imaging DSO's at 3250mm fl. I need my goto's to be dead on. At up to 600mm is so wide field you might not even notice it being off a little but at 3250mm fl. it becomes a problem.

I'm glad your Gemini 2 has no issues.



Neilson

Hi Terry. No...how do you do that? I'll do it right away!

Menu-HC-Buttons Then uncheck 'Persistant Diamonds,' IIRC.

I am using an unfamiliar Android tablet right now and can't figure out how to send a link here.
Try
www.gemini-2.com/stickybuttons.php

I was probably the worst offender of the stickies and was forever having runaways. Even after abandoning the membrane keys entirely for scope movement, it was easy to accidentally initiate a runaway by holding the HC and inadvertently pressing and holding a membrane key on the backside. After the feature was made user selectable in response to complaints, I deselected 'persistant diamonds' and have not had a runaway since.

I have not updated my firmware since July 2012. I just use the mount visually. Are the changes since then sigificant?

No.

Hi Terry D.
You stated your using fl up to 600mm. There's a big difference when your imaging DSO's at 3250mm fl. I need my goto's to be dead on. At up to 600mm is so wide field you might not even notice it being off a little but at 3250mm fl. it becomes a problem.

I'm glad your Gemini 2 has no issues.



Neilson

Hi Neilson,

While I am not currently using the huge fl you are using, I routinely use an AT8RC at 1625mm and like Terry I only use 3 or 4 alignment stars and the G11-Gemini 2 combo puts my targets on my ST8300 chip every time. Before I sold it, I did image with an 11" EdgeHD at 2800mm with a Canon 450d and my goto's were similarly as accurate. My experience with the Gemini 2 has been very positive in the 2 years I have been imagining with it so I have to give it a positive vote.

Hi Kirk,
Were they dead center every time all over the sky. My CGEM DX was dead center in the eyepiece and imaging chip every time. My G11 has yet to give me even one item dead center. I can even sync. then slew away then tell it to go back to the star and it will always be off from center or to the edge. Tonight I tried only a 4 star model after a polar alignment but my slews were off to the edge, even Jupiter was off.
I do have to say one thing, the moon has been centered most of the times perfectly. I would of expected it to be the opposite.

I know this is being nit pickey since at least a part of each DSO is in the eyepiece. But I feel since I paid over $1,000. more for the G11 than my CGEM DX it should be at least as accurate as Celestrons Nexstar. The goto accuracy was the one thing that impressed me the most on my DX. I read about others pointing out how their Celestron mounts puts targets dead center every time too. Even My Meade LXD75 and LX200R are both more accurate than my G11. I notice quit a few people using expensive goto software on their G11's. I wouldn't doubt they were wanting more accurate goto's as one reason. And if your mount does get every target centered every time all over the sky then that is great. But mine does not and I think it should.
This is not a deal breaker item but I think it should be addressed and corrected. Having goto's that are fine or ok or just good doesn't cut it after using much cheaper mounts with consitant excellent goto's.

I can't say Gemini 2 is better than Nexstar or even as good as it is when it comes to goto's.

neilson

I can even sync. then slew away then tell it to go back to the star and it will always be off from center or to the edge.

That's usually a symptom of a slipping clutch. A less common cause is bad encoder reads.

Hi John,
My new mount's clutches were slipping bad. I called Scott and he told me that I had the wrong clutches by mistake. He sent new different ones. Now my mount does not slip. They hold really good now and I am much happier about that. I was expecting this to fix my goto's. I have tested and tested but the problem is still there. I had hoped the clutches were the cause, but they were not.

Thank you for the suggestion.
I dont know how to test the encoders but I have switched the RA with the DEC motors then back hoping it might be a motor. But no luck there.

neilson

I dont know how to test the encoders but I have switched the RA with the DEC motors then back hoping it might be a motor. But no luck there.

neilson

The only other common issues (serious backlash or mechanical slop) are very unlikely in a mount of that class. The test you describe is perfect for diagnosing the problem, as it eliminates alignment errors completely. I'd watch closely to see whether the error on returning to the star is in one or both axes. If it's both, I'd look very closely at the OTA mounting for slop and look for backlash in both axes. If it's only one axis, then the first two I mentioned are still the most likely suspects but you can check backlash as well.

Hi John,
I have checked those things before but I will go back and check them more carefully tomorrow. I appreciate you helping me. Thank you

neilson

That's usually a symptom of a slipping clutch.

This would be my guess as well. I bought a $4.99 strap wrench from Sears because I could not hand tighten my clutches enough to keep them from slipping. The tri-knobs were too expensive for me but the strap wrench works fine. Even with the strap wrench, I've had slippage if I've not bundled the cables correctly.

Charlie B

Hi neilson,

Were they dead center every time all over the sky.

I set up fresh each night that I image, so I build a new model each time. I start (polar align) with getting all 3 stars set up in the PAS. I guess I am lucky as my PAS works very well (verified by occasional drift checks). When I am building my model I used to use a 12mm centering EP. The first star on a given side of the meridian is normally way off excepting a few very lucky times! The second star is usually in the FOV of the 8 x 50 finder and the third is usually very close to the center of my EP. Subsequent stars, if I add them are very close or dead on the center. I recently started using my guidescope (optics aligned to the main OTA) to build my model as it is easier to sit at my laptop and center stars than doing refractor prayers or contorting myself when using my imaging newt. It also saves me from having to rebalance the mount after I add the main imaging camera and filterwheel.

As for imaging, as it pertains to your question; at lower fl like on my 80mm APO at 480mm or my SV105 at 735mm pretty much dead on. No as much at longer focal lengths, but always on the chip. I seldom image what the goto gives me anyway as I am sure most folks like us will frame a shot after they find the object. There have been times that the mount has hit my target perfectly. It is not the rule though!

(Note: I normally only build east models and if I flip at meridian I add two stars in the west and use the bookmark feature to return to my target and do a manual plate solve if needed)

As to why you are seeing targets off center after proper alignment, I cannot explain. I have seen that as well but it always ended up being my own user error. Most commonly I picked the wrong star in the model. I'm not saying you are making mistakes, just commenting on why I think I have seen the issue.

On the subject of the G11/G2 costing $1K more than the CGEM-DX, I think it has a lot to do with mount construction and where it is made. I owned a CGEM before the G11 and IMHO the G11 is a better made mount using machined parts instead of sand cast parts. You certainly have a much better tripod than I had with my CGEM, so I have no comment there, only that the Losmandy HD tripod is much better than the original CGEM tripod. BTW I really loved and miss the Celestron firmware. Simple to use and as you said very accurate. It is certainly an area where Celestron has a clear advantage. Again, just my opinion.

I absolutely agree that you should be able to achieve more accurate goto's than you are currently getting. I would expect better than what you described.

Finally, (sorry for the long post) I am personally not happy about the lack of progress on the Gemini 2 firmware as of late. Sure it is functional and it gets the job done for me right now, but it could be better and there are reported and confirmed issues that need to be addressed as well as features that need to be improved(PAC for one!) and added (electronic assisted axis balancing).

Hi Kirk,
To me it sounds like your not getting much better accuracy than I am at longer focal lengths. At 480mm and such light weight mine would probably look somewhat centered just fine too. Its at longer focal lengths where it becomes noticable. I am using the exact OTA setup that I was using up until November on the CGEM DX.
I have a 9.25 Edge with a 2" flip mirror so I don't have to rebalance. I have an orion 80mm short tube on top with a DSI 2c as a guidescope. I use a 12mm illuminated reticule for alignment. I was even able to consitantly get my goto stars on the DX in the center of that reticule.
I level my mount with a nice carpenters level each time. I take time to balance my mount perefectly since its very sensative. I have never had a mount this picky about balance.

When I do my alignment I just use every star that the Gemini 2 gives me. Then I flip to do the West model then go back and redo several of the East model stars. I have marks on the ground to setup my tripods that I have used for years. I use "Polar Finder" software to tell me where in my finder to put Polaris. My PAC's accuracy is off about the same as my goto's. It was much worse before the new clutches. These clutches hold really good now.
I use leather work gloves to tighten them. I will buy the other knobs next month. Some times I do an East model, PAC, Drift, goto CWD, turn mount off then on(cold start) and start East/West models. Sometimes just a drift, CWD, off/on(cold start), then East/West models.

You mentioned that you did plate solving. I'm not experienced with that but it sounds like your using aftermarket software to help with your alignment. If so, Why are you needing that?

This accuracy is fine for wide field but not long focal lengths. It would of been ok 3 or 4 years ago but it's behind Meade and Celestron now. This mounts price point calls for better accuracy.

The Gemini 2 goto sells for $1,595.00 . The entire CGEM mount with goto costs $1,499.00 . The CG-5 is a lot less. That tells me the Gemini 2 costs about 3 times more than Nexstar. I expect it to be at least as good as Nexstar, not just acceptable. You mentioned how the mount is machined instead of cast aluminum. I agree, This is a higher grade mount. I think the firmware should be too. When I image DSO's that I can't even see, it would be nice if the mount centered them on my chip. Especially after all the work and time I spend doing a full East and West alignment. I don't think my mount is performing any worse than anyone elses who are using my fl. I haven't read anywhere that anyone who's using this mount with at least 3250mm fl without other software helping is consistantly getting all their goto's centered on their chip and/or eyepiece of 15 or 20mm. If Nexstar can have that good of accuracy then why can't Gemini 2.

neilson

Kirk,

Is PAC and axis balancing really that important to you? I think it's a neat 'gee whizz' feature, but there are so many other software options if that's what you're looking for (and doing AP). Otherwise, the current PAC is plenty usable.

I agree, I want them fixed too. But look at Synta's software, they're just now picking up PAC. Axis balancing is a relatively new concept too. And, neither of these are available for AP people (without other software).

I dunno, I'm pretty happy with where it's at. Definitely not Celestron, but it's not too shabby.

Celestrons All Star Polar Alignment is very accurate. I usually imaged without doing a drift alignment.
After doing PAC I still need to do a drift. Even after doing the PAC 2 or 3 times I still needed the drift. I did a drift then tried PAC and it had me move the mount out of alignment. Try it some time.
Usable, it depends what you consider usable.
And if your just doing visual or AP.

neilson

Neilson,

I'll just keep using something else then. I'm sure they'll get around fixing it someday. As long as it continues to control my mechanically superior mount... I'm happy . My issue with the CGEM was that it couldn't perform mechanically.

The MI250 rocks!

Hi Raginar,
I see you have an MI250. I just saw some pictures of one. That is an increadable looking mount. I wish I had one of those.
I recieved my new G11 mount with a number of serious mechanical problems. I blamed them for my Gemini 2's issues. But as the mechanical problems are getting fixed my Gem2 is still the same. Once my mounts mechanical issues are fixed, I wouldn't give it up for a Meade or Celestron mount. But I do find it hard accepting the Gem2 after using the NexStar.
I have been watching Rene fix things and add things that people want to make the Gem2 better, but only after its requested. If there are a lot of people saying the accuracy is good enough as long as its in the eyepiece somewhere then thats as good as it will ever be.
But if we ask him if he would improve the accuracy so that items are centered, especially DSO's for imaging, I bet he would do it.

And yes I emailed him a request to increase the goto and PAC accuracy about a month ago. But If others let him know its wanted he might go ahead and improve the goto's and PAC's accuracy.

Neilson