Thanks for all the comments! I've purchased an Ultron and will be hunting for a skopar. $500 was an academic limit to help inspire honesty and creativity. I have been interested in the biogon, but do you think the f2.8 version has anything over the f2 other than price?size? Weight? Image rendering?
I've heard very good things about the Ultron. The lenses it's routinely compared to that I
have used are incredibly good, so I'd have very high expectations for the Ultron, too.
Now, before I say anything else, I want to emphasize that many of us make it seem that fine distinctions between really good lenses are much more important than they really are. There are a lot of
really good 35mm lenses for M-mount cameras.
Both Biogons are also great lenses. I could have gotten either the 2.0 or the 2.8, and I chose the 2.8. I'm satisfied that this was for me absolutely the right choice.
It's smaller, and IMO the OOF rendering is considerably better. Not that the 2.0 is bad, but the 2.8 is to my eyes
flawless. Seriously, it's probably the best-behaved "standard" lens I've ever used on its technical merits (
flare supression, absence of distortion, sharpness, flatness of field, low astigmatism). But it's the bokeh at f/2.8 and f/4 that got me to buy the lens. I shoot a lot at those apertures.
I think it was a specific photo [the first of the four
shown here], taken with an M8, that was the final straw for me.
There are several threads on the lens. This is
one of them, and this is
another.
At some point I'll probably get a 1.2 Nokton for low light.