Reasonable lunar session at last, and some kit comparisons too

[Mr Spock]

For the first time with my new Rumak I've had a decent session on the moon. I've been waiting for my new iOptron 1.25" diagonal to arrive. The 1.25" I'd been using had been lying around for years and was really murky to look through; the iOptron is very impressive by comparison with an exceptionally clean, bright image. I also gave the Celestron 80ED an outing - I only usually use that for wide field but it's a more capable lunar scope than you might think.

The seeing conditions were what I expect for my location; wobbly at best with some fine detail visible. Decent enough at x144, but just going a bit soft at x200. Nothing like the acute 'spherical aberration-like' mess I had last week - that really was a hopeless night where even x56 looked poor. 

I concentrated my efforts on the terminator beyond Grimaldi. There seemed to be an area with a lot of fine detail. Also a few small, crisp looking craters. I won't attempt to say what they were - my id skills aren't that great. I must have spent an hour just looking at that small area.

Looking at the same area with both scopes at a similar magnification gave me a chance to compare. Firstly, at x150, the 80ED held up pretty well. A nice clean image with little or no false colour. It's easy to see why people like refractors. The 150mm Rumak at x144 went to the next level though. Despite the wobbly seeing conditions getting in the way I could clearly see more detail. Excellent contrast too - not like the slightly subdued feel you get with an SCT. I guess when I get some decent seeing it's going to spank the 80.

One horrible truth - the focusser on the 80ED is dire. It's stiff to move and has massive image shift. The scope deserves something better.

The session was cut short by my drive battery going flat. I must remember to put fully charged batteries in before a session...

[Mr Spock]

Apparently the interesting region and crater are on Montes Rook! I think that's a first for me.