Quote:
Originally Posted by slime
Does the secondary have to be perfectly centered looking down the tube?
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No, and it shouldn't be centred. If you you've done the right thing with your collimating it should be off-centre just a little. This is the offset, something that naturally occurs with today's modern short-focal length telescopes. To have perfect collimation the secondary should be moved
away and
down from the focuser to correctly intersect the light cone coming from the primary. Using a chesire will get this result automatically as part of the collimating process. The movement down usually needs to be calculated. It's more important a for big scopes, such as 16" and above, where its a significant shift.
A search of this beginners forum using "offset" should find some old threads where this has been discussed numerous times, and there will be some good explanations as to why there as well (better than I could do off the cuff).
In the old days, and with the older, longer focal length you did have to aim to have it centred but not anymore.
As for the flaring I would have said it was the eyepieces but if you're using televues I'm a bit stumped, sorry. Jupiter is bright, though, and its not uncommon in my experience to see a little bit from this planet.