p.1 #2 · Any thoughts on the Leica 5cm f2 Summicron Collapsible A5082601?
I had one and compared it to the vIII with which I replaced it. The coma and astigmatism did some funky things to the bokeh around the short edges at portrait distances and the flare resistance was low, but the veiling flare could be situationally pretty. The contrast, flare resistance, and overall correction were much higher on my 1970 vIII. If I remember correctly, the collapsible has a strange aperture shape to it.
I never measured the extension, but it went far enough beyond the e-mount adapter that I couldn't put a cap on it without it being extended a bit. I never tried collapsing it when it was on-camera. I'd been warned it could interfere with the shutter, so I actually kept a rubber band on it to keep it from going all the way down.
p.1 #3 · Any thoughts on the Leica 5cm f2 Summicron Collapsible A5082601?
I have both lenses. I believe that the optical design of Summicron Collapsible was derived from the Summarit 50/1.5 for the Leica LTM. When Leica introduced the M mount, they modified the Summicron design to account for the larger M mount – that is the main reason that the Collapsible and Rigid versions shared similar 7-element optical formula but different element geometric configurations. In terms of optical performance, technically, the Rigid is better with improved contrast and has larger zone for center sharpness at f/2. In other works, the Rigid version is a better corrected lens. But in actual use, I, personally, found that the Collapsible version, is equally excellent – particularly when used in B&W M mount digital body. I include two images below, Collapsible first and Rigid second at f/2 with M10R.
