So for the last 24 hours I've been toying with the idea of buying a refurb'd D3S. They're not that expensive, and a fraction of the price of a new Canon mirrorless. Insane high ISO performance. 12MP is fine for me. As I mentioned I have Dinny's old Nikon 50mm, which I have not used in the 15 years I've owned it. I also have a super neat Nikon 75-150mm F/3.5 E zoom (it has lousy CA, but the best bokeh I have ever seen.)
Well that idea is officially dead. I did some reading and (re)learned that it's not a good idea to mount M42 lenses to Nikon bodies. Nikon's flange depth is the issue. M42 lenses cannot reach infinity focus without an optical adapter that acts as weak tele-extender and reduces image quality. Canon does not have this problem.
I have an army of M42 glass. From amusing crap (Yashika 50mm F1.9, a very beat up Ashai Super Takumar 50mm F/1.4) to stunning and historic optical achievements (Carl Zeiss Jena Sonnar MC 135mm F/3.5, Tair 11A 135mm, Meyer Orestor 135mm F/2.8, Orestegor 200mm F/4, Orestegor 300mm F/4). Yes, I have more manual 135mm primes than a used camera shop and it's not like 135mm is a particularly useful focal length. Stop looking at me like that. The point here is there is no way in H E double hockey sticks that I am giving up all my manual lenses. I'd sooner buy a refurb'd 5D Mk II and I kind of hate that body (it was a sign of Canon going in the completely wrong direction: high MP count, lousy high ISO performance.)
My Meyer-Optik Orestor 135mm F/2.8 attached to a friend's Rebel digital body in '09. One zebra ring is focus, the other is aperture preset. The Orestor has a 15 blade aperture. This shot was taken with my 30D and my Tair 11A, which has a 22 blade aperture.
The Meyer-Optik Orestegor 300mm F/4 tank shell of a lens mounted to my Rebel K2 film body in '08, not far from where I'm sitting now. It has a 19 blade aperture. All of these lenses with insane number of aperture blades allow for absolutely sublime "bokeh shaping." It's so heavy it more or less mandates a tripod and still subject. I've mentioned this before but the 300mm Orestegor is a medium format lens with its own 35mm adapter. I've always wanted to buy an old Pentacon Six or whatever body and try out the 300mm with double the FoV and same DoF. I have told myself I'm not allowed to buy any more film cameras until I've built a darkroom. [I'm nearly 50 years old. I probably will not live to build a darkroom, but it's not entirely beyond the realm of possibility.]
Photo of the Tair 11A's aperture by Simon's utak on Flickr.
The 300mm Orestegor's aperture as captured by SteveFE on Flickr.
I don't have any photos OF the Jena Sonnar, but I have a few taken with it (what an odd idea):
Study of a bar ...thingy. ISO3200 on my 30D, which in general sucked at that ISO. Note how sharp the metal detail is and how pleasing the OOF areas are. The truth is, I have definitely not used the Sonnar enough. It's probably the best of the bunch from an optical perspective.
Bonus, SteveFE holding his Orestegor in 2006, propped up against his car so he doesn't fall over:
Me with the same lens, doing an imitation of Steve in 2009:
If the lens looks smaller when I hold it, that's because I have freakishly oversized mitts.
TL;DR: All digital camera bodies are ultimately disposable. Glass is forever. I have a thing for lenses with a silly number of aperture blades. I'm sticking with Canon.