Originally posted by Ben78 I have the Tak SMC 50/1.4 but the mirror hits the rear element at infinity focus
Yes, I've read about that many times. My adapter is an eb*y cheapo which doesn't quite allow focus to infinity. But, it does allow me to use my handful of Takumars and almost all of my numerous 3rd party M42s on my 5D with no problems. (Except for my S-M-C Tak 135 f/2.5 which has lugs that don't allow the adapter to fully screw on.)
I use my Canon for portrait style shots, so I don't miss infinity.
Quote: Is the 55 all that different to a 50? I've always thought of them as being too close in fl to make much difference
That probably depends on who you ask. I'm primarily a backyard snapshooter, and in my view, no, there isn't a great deal of difference.
I chose the Auto Takumar 55 as my example because it's the smallest lens I own.
Here's a 5D comparison between my Super Takumar 50 f/1.4 and my Auto Takumar 55 f/1.8
(shot on a tripod from the same position):
Super Tak 50mm f/1.4 @ f/2
Auto Tak 55 f/1.8 @ f/2