I have an early collapsible Summicron LTM that I used with an M adapter and a rubber lens shade. Shot with it Sunday, indoors B&W, and found the resolution at the closest focus range to be just fine. It does tend to be less contrasty than the later ones, but I haven't tried the most recent model. The nice thing about the collapsible is the size of the camera in the bag or pocket. I was lucky with this lens and bought it quite some years ago. It has no cleaning marks, oil, or fungus. A wonderful lens that doesn't get used enough.