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View Full Version here: : Skywatcher (8 inch) focuser

Dan31415
05-04-2006, 01:05 PM
I was out observing about a week and a half ago and the conditions were about the worst you could ever think of. The temp was about 30 (this is at about 9:30 - 10:00 at night!) the humidity must have been about 90% and the sky was covered in low rain clouds with a only small window of opportunity (break in the clouds) for viewing Saturn. It was that humid and hot that I was observing just in boxer shorts! (I was not in a public place) and I was still having to wipe my brow from sweat every couple of minutes. It was that hot that there was condensation on the bonnet of the car. Anyway even disregarding these conditions (and a very quick collimation using a film canister) the view of Saturn was surprisingly good. I could clearly see one of the belts in Saturn and the Cassini Division at about 140x. Anyway, I would focus on Saturn and then about a second or two later it would be out of focus again - it just wouldn't hold focus.:sadeyes:

Is this what is referred to as focuser 'slop'?

Oh, the focuser is a stock 2 inch R&P. I know that the focuser was that great when I bought the scope and always had the intention of up-grading it.
ving
05-04-2006, 01:26 PM
i dont think it was the focuser... probably changes in "seeing" was the problem. seeing often isnt constant :)
rmcpb
05-04-2006, 01:29 PM
From the conditions you have described I would bet on variable seeing and really thin cloud cover getting in the way. Your focuser is not to blame for this.
Dan31415
05-04-2006, 01:58 PM
Oh, I just wouldn't have thought that the 'seeing' would make the image go out of focus once it was in focus.
janoskiss
05-04-2006, 02:16 PM
It does not do that, but it can seem like that. It goes blurry and then you are tempted to play with the focus again. And then you keep adjusting till you once again get a few moments of better seeing and think you got it back in focus. But 30 secs later it's gone blurry again because the seeing got worse. So you go back to playing with the focuser and so on and so on ... drive yourself bananas ... :rofl: I know. I've been there, done that. :reindeer:
ving
05-04-2006, 02:19 PM
ditto steve, i think most of us have :) (recently for me too :ashmed: )
Dan31415
05-04-2006, 02:26 PM
:thanks:

thanks fellas! so what is meant by focuser 'slop' then?

Dan
ving
05-04-2006, 02:55 PM
slop: you can wiggle the tube around in the focuser... i think :confuse3: