This is an exquisite lens.  Glass is flawless.  I've used this lens extensively.  It is extrememly sharp and renders fine microcontrast very well.    This lens has 6 elements in 5 groups, which I think is perfect. This is a John Rudolph (Zeiss) Planar derivative.  Uncommon at 35mm focal length, 8 aperture blades produce ultra smooth bokeh.  No; hazing, fungus, scratches, nicks, cleaning marks, elements separating.  Focus might be smoother than my Pentax M series lenses.  Aperture is nice clicking and without any oil on blades.  This lens has a manual/auto switch which allows you to stop the aperture down when using it on a dumb adapter.  Mamiya Sekor made several 35mm lenses.  This was their best.  It compares well with My Pentax and Distagon and the optical formula is nearly identical.  However, this one has more aperture blades than either.