dmsummers wrote: I can't quite follow your math. If you connected the extender at 55.2 (59.7 minus 4.5), then subtracted 40 for the spacer and 12.5 more for the sensor recess in the camera housing, doesn't that still put you 2.7mm shy of intended backfocus position? Did I calculate this wrong?


According to the diagram, the image focuses at 77.7 mm from the edge of the ring with the numbers on it. Attached to that ring, I have 24 mm worth of other rings, the last one of which I added a 40 mm extender to, to which I added the camera, (12.5mm), so 77.7 - (24 + 40 + 12.5) = 1.2. I figured I could compensate for the 1.2 using the manual focus of the Spacecat.

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