Quote:
Originally Posted by Renato1
Don't panic just yet.
Even with perfectly collimated optics, on some nights you won't have much luck.
If the stars are twinkling - you won't have much luck with sharpness.
Even if they aren't twinkling, some times you won't have luck with sharpness.
If you are viewing from suburbia - with neighbours having their heaters on (or air conditioners on in summer), don't expect much sharpness. If you are viewing over your heated house, don't expect the best.
If you aim at a star at high power, and throw it out of focus, and you see a bulls-eye pattern, then you can see whether you are nearly collimated or not (the black bit of bulls-eye is not central, an dyou have to adjust the three screws at the back of the telescope to get it central). Unfortunately, my 14.5" dob is my only telescope that doesn't give a bulls-eye pattern - I have to use an aperture mask to get the bulls-eye to show up. I don't know whether a bulls-eye pattern shows up in your telescope.
If your mirror has a black dot in the centre, a Cheshire eyepiece and a little flashlight will let you collimate the telescope pretty close. Though, as I was advised here a few months back, an Autocollimater gadget is needed for precise collimation to get the absolute best out of the telescope.
Laser collimators are around. I've bought one, but haven't actually used it yet, so can't comment.
Regards,
Renato
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Thanks very much. I was out last night but only briefly and too late because Saturn was too low in the sky to see - behind trees. The moon looked good again and I do think it's pretty clear. I tried to defocus some stars and I think the collimation may be slightly out. Unfortunately, I didn't get the time to try to make adjustments while outside last night. I'm really hoping for a clear night tonight so I've got a few hours to try again on the collimation. I now think seeing conditions are not that good where I am. When I look at the edge of the moon, there is a lot of shimmer, like heat. When defocusing a star, I'm not getting the clear circles I see when I google star collimation images. My defocused star is hazy even when the circles are concentric. Thanks again. I'll take the laser collimator and cheshire out tonight and take my time on the collimation. Cheers.