Summary

Holder which mounts microscope objective lens (reversed) on Raspberry Pi Camera v2.1 board. Connects to PCB with 4x M2 screws + nuts. OpenSCAD file can be modified for other objective lenses. This one fits an AmScope 4x objective http://www.ebay.com/itm/381613828736 which acts as a long telephoto on the RPi camera (250 mm equivalent on a full-frame SLR). UPDATE: added optional part; a mounting ring with pocket to capture a 1/4-20 hex nut, to accept a standard camera tripod mount.

The resolution test (ring pattern) above is a 1:1 crop of the 8Mpixel camera image, showing a target measuring 18 cm across the "T" marks at a distance of 9.6 m. I calculate this lens has f=27 mm and HFOV ~ 8 degrees on this sensor.

You do need to remove the factory lens first, so the sensor is uncovered. You can use one of the lens tools to crack open the glue on the lens thread; either http://www.thingiverse.com/thing:1557754 or http://www.thingiverse.com/thing:1574661

UPDATE: For anyone needing a long lens for the RPi v2 Camera, I now recommend you consider printing this M12 adaptor mount http://www.thingiverse.com/thing:1963856 for use with a M12 lens such as http://www.ebay.com/itm/282167088666 which I have found has good image quality. Perhaps better than the microscope objective used here.