TheSkySearchers

I mentioned briefly in my short report about using the Nexus II for the first time a focusing issue with my AD10.

Here's the history:
Up until 2-3 sessions ago there were no problems. My 18mm (2") and 11mm/6.7mm (1.25") all went into the focuser with no issues, focused just fine (with the adaptor for the 1.25").

2-3 sessions ago, I collimated twisting the secondary a bit - the 18mm would not come to focus, even with the focuser at FULL travel. however, when I added in the 35mm extension tube - focused. The 1.25" were fine in the focuser without the extension tube.

Sunday night - I started to need the extension tube for the 1.25" EPs as well.

I have no idea what's going on - does anyone here have any ideas?

I can use the 35mm extension just fine - but I don't understand why all of the sudden this is happening.

I guess it's possible that this COULD be the difference between observing with my contacts (Normal) and Glasses (lately).

My Glasses usually come off, and I have astigmatism on both eyes....Doesn't seem possible, but I guess, as I said, it COULD be.

Hopefully my new contacts come in before my next session, and I can experiment.

Is the telescope at ambient temperature?
It seems a bit strange it would work and then not.

Lady Fraktor wrote: ↑Wed Sep 02, 2020 5:03 am Is the telescope at ambient temperature?
It seems a bit strange it would work and then not.

Yep. It lives in a shed outside, and when I set it up, I Run the mirror fan for about 45 minutes before observing.

I had it out yesterday after work, so no fan, and it wouldn't focus on the trees some distance away without the 35mm extender.

Maybe do a double check on the collimation adjustments you just made. Maybe put it back to the way it was.

Cheers,
JT

Yeah, I was thinking of just "backing" everything out (for lack of a better term) and starting from scratch with the collimation.

I was just going to suggest pulling everything back as your mirror may be to far forward now.
Hopefully it is something this simple.

Are those trees nearby? A close by object needs far more outward travel of the focusser than an object at infinity, like a star.

John Baars wrote: ↑Wed Sep 02, 2020 8:11 pm Are those trees nearby? A close by object needs far more outward travel of the focusser than an object at infinity, like a star.

They are *probably* too close - a couple of streets away, but I have been able to focus on them in the past without the extender tube.