Mary wrote:
I have a Nextstar 8" with the goto feature. While trying to sharpen
the focus, I turned the focus knob too much and now I have a big black
circle in the middle of everything I look at. (I assume it's the
shadow from the secondary mirror. I've tried to get rid of it by
turning the focus nob back, but it doesn't help. (The circle moves off
to the side and the image gets smaller and smaller.) What have I
done? I think I broke it. Help!

The image should get smaller as you approach focus. There will always
be a circle in the center of the star image if out of focus (looks like
a donut).

And focusing moves the primary mirror and can result in the image moving
to the side, especially with high magnitudes.

You should be doing all of this with a 25 mm or so eyepiece, not a high
magnification EP.

It seems so long as turning the focus control has some effect, it may be
working. OTOH -- it could be broken. I'd have the dealer or some
experienced amateur (e.g., in your local club) have a look at it.

It might help if you mention roughly where you are located: You might
get a volunteer g

Phil