I have tested out a Pentax Super Takumar 55mm f2 on my Fuju XE2
I took three shots in aperture priority with the following results.
The first shot at f2 was definitely soft but with a beautifully even bokeh.
The second at f5.6 was sharp also with nice progressive bokeh
The third at f16 had a much extended depth of field but diffraction had started to soften the finest details.
I then fused all three in TuFuse Pro which selects the best pixel to use to create the final image. Though the f2 shot contributed nothing to the exercise, the resultant fusion was an improvement on both the f5.6 and f16 shots but is only of academic interest.
conclusion...
The Super Tukumar 55mm f2 produced a sharp very pleasant image with great smoothness, and very unlike the critical hard crispness of a digital generation image. It would perhaps make an excellent portrait lens for use on a digital camera.
All the images were unsharpened and unadjusted processed from raw. Red arrow shows focus point.
These are a crops at 100% slightly downsized to comply with image size rules.
no 1 f2 by
Terry Andrews, on Flickr
no 2 f5.6 by
Terry Andrews, on Flickr
no 3 f16 by
Terry Andrews, on Flickr
no 4 F2-F16 fused by
Terry Andrews, on Flickr point.