losmandy G11 gemini 2 mount question !
Posted 05 May 2013 - 09:55 AM
Posted 05 May 2013 - 10:29 AM
After first receiving my mount from Losmandy, it bound and made horrible screeching noises. I adjusted the worms until I thought they were correct, but still had tracking problems, especially in DEC. The best advice, which I followed, was from a post by Ed Thomas at Deepspace Products. He suggested adjusting while slewing. I put the mount on a bench, loaded enough to keep balance, and slewed with the handset, while adjusting the worm, until it sounded correct/good. I checked that the play/backlash was minimal and considered it good to go.
Performance, fully loaded with my SN-8 and astrophotography gear (about 35 lbs), was good with about +/- 15 sec PEC, corrected to +/- 5 sec with Pempro. It tracks good and pointing is good.
Posted 05 May 2013 - 01:15 PM
Posted 05 May 2013 - 01:25 PM
the tracking was frankly horrible! used a 8"sct @ 6.3 ( 1260mm fl and prime w/ dslr ) and there was a lot of tracking and some weird triangle shaped stars in my images ( around 45sec to 60 sec subs unguided ) nothing worth keeping. I chalk a lot of that up to not creating good models only one star but was very disappointed. Rex
The tracking issue has nothing whatsoever to do with modeling. Unguided at 1260mm fl is not going to work well and you can model build to kingdom come with an infinite number of stars without it improving. You need to guide. And how is the polar alignment? That matters too but modeling does not.
Posted 05 May 2013 - 04:18 PM
thank you Charlie, I will do that. I took the mount out last night to star party and did some quick alignment and goto modeling ( still leaning g2 menues ) and the tracking was frankly horrible! used a 8"sct @ 6.3 ( 1260mm fl and prime w/ dslr ) and there was a lot of tracking and some weird triangle shaped stars in my images ( around 45sec to 60 sec subs unguided ) nothing worth keeping. I chalk a lot of that up to not creating good models only one star but was very disappointed. the goto was very nice for my first time out but tracking needs work. apparently they update and change the g2 OS often so I guess that rules out an actual manual for this mount. love the construction of this mount it really is a work of engineering art. plan on getting many years of use from it. thanks again. Rex
As I understand it, the modelling has to do with pointing accuracy and not tracking performance.
Judging by the reports of G11 owners that I have read in various places, improving G11 RA tracking is some sort of rite of passage: you get your G11, the tracking sucks, you do some tweaking and fiddling and finally the tracking gets to be what you dreamed about.
At your focal length, I suspect that you can do unguided astrophotography only with the very premium mounts and after obsessive polar alignment.
Waiting for some favorable weather so that I can go out and play some more with my RA tracking.
Posted 06 May 2013 - 10:30 AM
Posted 06 May 2013 - 10:52 AM
It would be really rare achievement with that mount.
Posted 06 May 2013 - 11:39 AM
Posted 06 May 2013 - 11:41 AM
Welcome to the club! I have/had a G11 that started with the Digital drive & wound up with with G2 & the OPW before I got an HGM-200 for more capacity. I believe that someone has already spoken for the G11. When I got it it wasn't a very happy camper, Old grease, steel worms, squashed clutch pads. I cleaned & greased & tweaked until I was ready to put it in the dumpster. It gets better. The OPW is fairly straightforward to adjust. This is what I do YMMV:
While assembling the OPW make sure that the end bearings have the smallest play by squeezing them together with your fingers while tightening the hex bolts. This will get the end play down to a minimum. Don''t use a 'C' clamp like was need on the old style worm block assemblies, it'll only cause bigger problems.
Once the end play on the worm has been taken care of, install the coupler with a IIRC 0.001" clearance. Be aware that the coupler will only work one way IIRC.
At this point I installed the OPW on the mount without the gearbox, but with the Gearbox studs in place.
Put the hex bolt closest to the motor on 1st and snug this up. The idea is to use the hexbolt farthest away from the motor to hold the OPW in place and use the hexbolt closest to the motor as a pivot point.
Back the thumbscrew all the way out, then gently push the OPW against the Worm Wheel (RA/DEC Gear), and rock the worm wheel to seat the OPW into the wheels teeth as far as possible, then tighten the hexbolt farthest away from the motor.
Finish assembling the OPW, with the Gearbox, motor cover, motor, etc. Don't tighten the hexbolts all the way down yet.
Gently snug the thumbscrew up to the OPW. Only a very light tightness is needed.
Put the OTAs' finders, Guiders, etc., & balance normally.
Start Gemini, & manually slew the mount using the OPW that you just installed.
When you hear the mount start to bind, stop slewing, leave the mount tracking, and loosen the hexbolt farthest away from the motor, turn the thumbscrew 1/8 turn MAXIMUM, then tighten the hexbolt again. It doesn't take much adjustment.
Slew the mount, to check for binding, & readjust as needed until you can slew from limit to limit without binding.
Now tighten the hexbolts so they don't move.
Do the same for the other Axis if you need to. Done.
As has been mentioned there is are several groups that are run by users. The Gemini-2 group is an excellent & very active group run by Tom Hilton as a service to the users. Well worth your time. Good luck.
Clear Dark Skies
Posted 06 May 2013 - 12:37 PM
Once the end play on the worm has been taken care of
I forgot that I had to take care of this problem too. However, you will find that the G11 is very easy to work on.
Posted 06 May 2013 - 04:23 PM
Posted 06 May 2013 - 05:42 PM
just for the record, I have only had this mount since 5/2/13 and have been working with it and trying to get accustomed to it.the mount is brand new and the factory (losmandy) installed the worm block an precision worm. one would think they would have put a little effort into trying to make it right. you don't buy a new BMW and then they tell you the cars doesn't work and were not going to give you a Manuel and oh by the way you will have to talk to other owners of the car to figure out if you can get it to work! hey do you want custom floor Matt's with that oh well that was my 2 cents worth now to get it to work, joined yahoo losmandy group and with all of your help as well hope to have some nice images to share and stories to tell .
Interestingly enough, the notion that one could fiddle with and adjust the mount was one of the factors that led me eventually to the G11. My mount is almost as new as yours. Our weather has allowed me only one fairly extended outing. I did report that experience in this forum. It was not all positive, but then, in this hobby is anything ever all positive?
Posted 06 May 2013 - 11:57 PM
I have been thinking long and hard about the G11 from my personal experience and I have come to the following conclusion.
1) I have only tried 1 other GEM made by Synta, it had no GOTO. I think it was an equivalent of the EQ5 but at the time I didn't know enough to be sure. Anyway, the quality of that mount was horrible and it did lead to personal injury. I am still carrying the scar since 2006. The G11 is a Ferrari in comparison to that piece of junk
2) The G11 out of the box performs badly, it needs a lot of tuning, this gets on my nerves as it is not the cheapest piece of gear out there, and as you mentioned it doesn't even come with a printed manual for the price. That being said, once it has been tuned, it will perform to a very high level of excellence. Till the next time it needs tuning again then you go through the entire song and dance again, only now you know a bit better and are less likely to get it wrong.
4) For visual use the G11 performs admirably with minimal fuss and it can carry a very big load.
5) The only reason to buy a G11 for imaging is that you cant afford a Mach 1 GTO or Paramount MX.
At the end of the day, it is a very capable mount, but it is very frustrating to get it to work to the best of it's capabilities. I've had people show me unguided photos taken at 2000 mm done with the G11, that is an amazing achievement. On the other hand, I had spent more than a year struggling with mine till it started to behave, if I totaled the hours, it might come close to 2 working weeks. If I add 2 weeks salary to what I paid for the G11, I would have been able to afford the Mach1GTO. That is something to consider.
Would I recommend this mount to others? Depends on the following:
1) Are you financially constrained? If no no, don't bother with the G11
2) Are you capable or willing to put the hours needed to make this mount deliver on it's promise? If no, consider sending for a "Hypertune" or just get a cheaper mount and be satisfied with imaging at a shorter focal length.
3) Are you in a country where Celestron and Meade don't sell their products and are thus considering the G11? Consider Synta, AP, SB and Takashi mounts. Or open an account with Shop 'n' Ship and just get the celestron mount you originally wanted.
The G11 is the mount you buy when you have no other choice for the sort of work you want to do with it. I honestly believe the design is antiquated and is due for a refresh, specifically in the worm gear adjustment mechanism. I don't hear people with other mounts complaining so much about the worm gear adjustment mechanism.
Posted 07 May 2013 - 03:24 AM
It was not all positive, but then, in this hobby is anything ever all positive?
Yes.. when I got a Mach1 it was all positive.. (except for the hole in my pocket)
Posted 07 May 2013 - 06:09 AM
I'll start a separate thread with updates on how well it works once I get it. I figure that it is a very reasonably priced upgrade to get and from what I read on the internet, I don't know of any unhappy customers.
Posted 07 May 2013 - 10:55 AM
Posted 07 May 2013 - 11:28 AM
I was about the very first customer there was for a G11 with Gemini 2. (Only half joking!) The system was considerably less than half-baked when I bought. But I was clueless and didn't know. A few months later Gemini 2 was far more capable and I did AP happily with camera lenses up to 600mm in FL. I was pretty pleased. My G11 seemed to behave well "out of the box" and with nothing other than the standard worm . . . not Ovision and not OPWB. I have lots of images that I am still happy with.
Then I went to a mono CCD camera and NB imaging. Still with relatively short camera lenses (as compared to telescopes!).
I still got some nice images . . . but . . . things began to "go wrong."
The longer subs, 15 minutes at 600mm, sometimes even 30 minutes, began to become "hit and miss." Still lots of "hits," mind you. "Hits" even at 30 minutes . . . as long as I was well off the meridian. But I became more discerning and more "picky." I began to be . . . well . . . less happy.
I got star elongation issues. I blamed flex and went to Herculean efforts to ensure my, still very short FL as compared to telscopes, lenses were rigidly mounted. The elongation issues persisted, especially near the meridian.
I got increasingly frustrated. I could not figure out why this was happening. I had absolutely no trouble at all adjusting my RA worm. I took all noticeable backlash out of it with no trouble. Had no binding issues. Still had lousy subs near the meridian though. Why????
I wanted to go to a longer FL . . . a "real" telescope for galaxies,SNRs and planetaries rather than just "wide field" images of HII regions.
It seemed to me I had to make a huge change!
Was it the G11 that was the source of this star elongation issue?
I still don't know. I did know I did not want to fight this battle any more! I had beaten the flex demon into the ground but still had too many lousy subs. I was beaten! Trying longer FLs seemed absurd.
It was time to either give up AP, or move on and take it to "a higher level."
I waffled. Then I decided.
I sold the G11/Gemini 2. I am still without a mount. I will buy an AP1100 as soon as AP tells me they have one to sell me. Yes, I decided to skip the Mach 1. I also decided to wait it out for the AP1100 instead of getting an AP900 immediately, a decision I question with every clear, moonless night that passes.
I don't "diss" the G11 as I still don't know if it was the problem or not. And, I did come to absolutely love Gemini 2. It is an amazingly capable system as far as I am concerned, despite all the lengthy growing pains that still continue even to this day. I feel I will still miss Gemini 2 even after getting the AP1100. I have not tried the AP software yet, but I gather it is "primitive" compared to Gemini 2.
Some of the problems that are reported with the G11 perplex me. Yes, I feel sometimes it is user error. I had no trouble adjusting my worm . . . "easy as pie." These reports of "grinding," and "screeching" gears I do not understand. It just was not my experience. It seems a pretty simple beast to me, rather easily adjustable.
But I could not get nice, long NB subs even at very short FLs. I still don't know why.
Posted 08 May 2013 - 12:00 AM
Posted 08 May 2013 - 12:00 PM
if you are mechanically inclined and like working on stuff like this then you'll probably like the G11 a lot, because it is very robust and mechanically simple.
the Gemini-2 does have some annoying bugs as well and of late firmware support has not been that great.
i moved to a mach1gto but the ap1100 is the real deal for sure. you're not going to have any hair-pulling problems with that mount.
Posted 31 May 2013 - 08:18 PM
at all or since. It is the Digital drive and I am hoping that somehow it's a glitch with the hand controller that something is stuck. Anyhow lll be fiddling with it soon.
Posted 02 June 2013 - 10:32 AM