Hop-On Hop off Bus, M and Adapter

[Rocky]

I was on the Hop-on Hop-off bus in Europe for a few dates. This is an eye-opener. The Slow AF of the M makes it become useless. A good MF lens will be a good solution assuming the adapter is in "perfect" registration for the extension. After getting home I try my old Summicron 2/35 (56 mm in 35 mm equivalent) with the LM to EF-M adapter. That will be a good focal length for the bus tour. To my surprise, focusing is OFF. Subject at infinity is in focus when the lens is set at 11 meter (33 ft).Upon calculation, the adapter is shorter by 0.11 mm (0.0048 inch). A heavy weight office paper is the "perfect" thickness. I made a paper ring with all the necessary holes to put between the LM mount (front part) and the adapter body to shim the length. Now the lens infinity mark gives me the real infinity focusing. I hope someone can benefit from my experience.