View Full Version here: : Jupiter's Blob

08-08-2017, 06:39 PM
I tried out my new scope a few nights ago (10 inch Dobsonian telescope)
and I found that the moon looked quite nice (and bright) and crisp through the scope, however, when I sighted Jupiter, the planet did not look really crisp enough, same with the moons, I moved the scope around Jupiter a bit and noticed the light was like bouncing off of sorts.

Could this be perhaps that the mirrors are slightly off their alignment?

I noticed that stars weren't 100% clear either.

The first night I took the scope out and immediately started observing, the stars and Jupiter's moons weren't clear, as if they where out of focus.

I was trying to focus them but was could not get crisp images.

I could barely see Jupiter's bands at 200x. ( It was quite bright though understandably due to aperture.)

I left the scope out for about an hour, went back and the moons and stars looked better, though, I feel that still im not getting the clarity and crispiness that I should.

08-08-2017, 07:36 PM
Have you checked Jupiter etc. over the span of a couple nights to rule out any atmospheric distortions or other conditions that may have messed with your ability to get a crisp image?

I'd say make sure that you get all the basics right (including letting your scope cool down sufficiently) and then compare over the course of a few days.

With a mirror that size you'd be well advised to collimate it now, and frequently thereafter - so you should get going on that topic anyway.

08-08-2017, 10:11 PM
It sounds like at first you were definitely dealing with a mirror that was still cooling down. If you looked at Jupiter at 200x just after taking the telescope outside I can imagine that it would have looked pretty soft.

Seeing conditions are another issue, when the seeing isn't great (like it has been in Vic for ages!) then it doesn't matter how long the 10" is out, anything over 150x will just look soft not matter what.

Collimation is another aspect that robs contrast away from the planetary views. The moon is very forgiving :)