Hi,
I have just recently bought an 8" f/6 Discovery dobson. So far I have spent
4 nights observing and it was very nice. However, I have 2 problems.
1. My focuser (2") moves not only in and out of the tube (to focus the
image), but it also moves up and down (about 1mm). Depending on where the
focuser is, collimation can be anywhere from okay to way off. I was thinking
about buying a new focuser but I don't want to spend more that $100 on it.
Are the Orion focusers any good?
2. When I collimate the optics it seems that the reflection of the spider in
the main mirror is not in the center of the main mirror (this could be an
optical illusion - I'm not sure). I didn't want to mess around with it, so I
left it alone.
Last night (dec. 26th 1:30 - 2:30am, Saratoga) I checked out Saturn and
Jupiter at 200x (6mm Radian). I let the scope cool down for about 30
minutes. I could make out the cassini division but it was not very clear. On
Jupiter I could see 2 dark cloud bands with a white region in between them
and 2 more white regions at the poles. I could not see the great red spot
(according to calsky it was visible). The images didn't seem well focused.
Moving the focuser up and down (not in/out of focus) and refocusing the
image afterwards didn't improve the image.
I was wondering if somebody could take a look at my scope sometime next week
(when the weather is nice) and give me some advice on what needs to be done.
Thanks. Happy holidays and a happy new year,
Géza Kurczveil
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