M12 Mount for RPi Cam v2 (mod)

This is a tweak to vaqueram's M12 mount to allow the use of longer M12 lenses that need to sit closer to the sensor. On this one, nothing prevents you from screwing the lens right down against the sensor block (so be careful). As with any M12 mount, you do have to remove the tiny factory-stock lens from the sensor block first. The Raspberry Pi camera board I got from Amazon came with a round white plastic tool meant for refocusing the lens, but it also works for just removing the lens entirely.