David Murphy
Veteran
I've owned and used the Summaron 3.5cm F3.5 and I was happy with it. It is not the sharpest 35mm lens out there, but pretty decent and very compact and well made too. I have not used the Canon 35/2.8, but my experience with other Canon LTM lenses is that the "black" models have better optics (sharper and more contrast) which I am sure is a consequence of tighter construction tolerances, better optical glass, better coatings, and perhaps in some cases recalculated designs. The Canon 35/2.8 is usually a little less expensive than the Summaron on the used market.