HELP !! Mount problems...

Keith --

I don't think re-greasing the RA drive is going to help. If it were being "jumpy", the stars would be streaking along their direction of travel, not perpendicular to it.

I also don't think the 3-star alignment will help -- that can only tell the mount how far off your polar alignment is -- but the only way to correct for that is to run both motors, which will introduce a bunch of other errors (so you don't want to go there). A 3-star alignment will likely improve your GoTo's, but that's not what we're looking for here.

Level on an equatorial mount shouldn't matter either. (It does make polar alignment easier by preventing the two axes from interacting -- so that changing the azimuth affects only the azimuth -- but that's about it.)

How are you doing your polar alignment? Does your mount have a polar scope? If not, are you just sighting in on Polaris? (That won't work well; Polaris is actually most of a degree off the celestial pole.) Or are you using some polar alignment routine built into the mount (for instance, one which has you center a non-Polaris star, go back to Polaris, and then remove 1/2 the distance using the mounts altitude and azimuth adjusters)? These routines don't work terribly well either -- the only guarantee is a good drift alignment (although some of the better polar scopes can get you *really* close).

-- Jeff.

Thanks Jeff

How are you doing your polar alignment? Does your mount have a polar scope? If not, are you just sighting in on Polaris?

Polar alignment is done all manually, been doing it now for years, but I align my 9x50mm finderscope first, level the mount etc. before polar aligning. Ihave a detailed map of the north celestial pole down to 8th magnitude, so it's relatively easy to come very close to the actual pole when aligning.

However, I don't have a polar scope. All I know is that when I got the mount in May, it gave me good 2 minute unguided photos for about 2 months, and then this, without any work on the mount at all. I'll probably regrease anyway, maybe it's the only thing bar autoguidind that I got left....

Keith..

Keith --

I'd highly recommend a drift alignment. It's a total pain in the arse to do at first (you'll need to bring out a cheat sheet giving the various directions to move the mount to counteract the drift), but it's the only way to know for sure how accurate your polar alignment is.

Still, it is odd that things were working before and now they aren't. (It'll probably be something obvious in hindsight once you have it sorted, but that's not much help beforehand.)

Anyway, good luck with it (and let us know how you get on).

-- Jeff

Aw man looks like my cg5 goto is a lemon, after such effort to regrease the right ascension axis last weekend, and the dec axis a few weeks before that, it was the acid test the a few nights ago, and here is the result....absolutely the same as before, star trailing from top left to bottom right, the bright star is alpha persei, rising in the northeast sky.

Also visually, I noticed that the bright star altair was visibly 'wobbling' from bottom right to top left when looking through the eyepiece, which was a correct 'right side up' view. I am so dissheartened.... :roll:

Will autoguiding take care of this? maybe it's a doubt as this is only a 30 second shot....could the mount be adjusted that quick? Maybe i'll stick to widefield shots, and leave this side of astro to you guys :lol:
Keith..

Keith --

If it's any consolation, I regreased both axes of my LX200GPS (twice each), adjusted the spring tension (several times), adjusted the limit stop setscrews, replaced the motor controller boards, replaced the motors, replaced the worm and worm carriage, adjusted the preload on the bearings, and bought an oscilloscope to try and figure out what the electronics were doing. Never did fix it. I've now got the OTA mounted on a GEM.

-- Jeff.

I've now got the OTA mounted on a GEM. Neutral

Ah! don't feel so bad now it's a pity you had to go through all that , like flogging a dead horse.....

Maybe one day i'll save enough for a mount like yours...
Time to dream on for now..

Keith..