Dave and jrista,
Thoughts turned into a momentary urge to purchase this AM, so I'm committed. Thank you both for this helpful commentary and eye opening initial dose of information. Since I'm retired I have a fair amount of time and am simply bitten by the bug of photography. I was bitten back in 1974 when I first bought a Canon Ftb but the responsibilities and cares of life just didn't allow it to materialize much, although I had purchased an F1 and a few lenses and always shot family and travels and a little wildlife. But now - wow. The technology has advanced so much that results are close to unbelievable.
In terms of star images, I love the scenes that include landscape and wide angles and have followed threads on CR and elsewhere. A friend who's a few years ahead of me in all areas or photography already knows the basics and so he's there in the background chompin at the bit. We've both splurged on some gear and he recently bought a 1Dx and a few lenses. Now I know why an eternity ago my mother said be careful about choosing friends, they can be a bad influence!
Anyway, at my age I can now start to revert to my childhood flitting as a butterfly from flower to flower having fun and exploring more of our fantastic world. Birds have been great fun this year but in the winter snow I don't have many birds. However, I do have Northern Lights and lots of stars given that I'm about 15 miles from the city with not too much light pollution, so I'll be doing my best to learn with help from the many kind folk on CR like yourselves.
Another friend who is a former student of mine in electronics technology is now in the photographic picture and he's a technology geek and programmer having fabrication skills and a creative spirit. We both have lathes, etc., and love doing metalwork and so with his recent motion control projects there are no end of possibilities. Personally, I'm trying to stick more with photograhy and not get sidetracked but fun is fun......
I hear good things about a Rokinon lens that I may buy but initially I was hoping my new 70-200 F2.8 would work on the mount, or my 24-70 F4. I guess only time will tell where all this leads me and I'll soon know what isn't working. Thanks again for the advice.