dan3008 wrote:Is there any chance you'll be selling the board and attachment pre-assembled?
Yes, I can sell assemblies with a new camera module. For the moment I only have two extra camera modules on hand, and I hear they're not going to be available for another month or more.
The riskiest part of the installation is disassembling and removing the stock lens, which is indeed delicate. But if you're comfortable with that, then assembling the M12 adapter itself is trivial.
jbeale wrote:I gather the M12 lens holder is indexed to two holes on the camera PCB, rather than the existing lens mount?
jbeale wrote:I am wondering about using very short focal length M12 lenses with a back-focal distance small enough (few mm) that it would require removing the existing M6 lens housing from the sensor chip.
I optimized the adapter to fit the widest range of lens characteristics possible. I carefully analyzed the clearance available on the Raspi stock lens receptacle versus a list of mating thread engagements and back focal distances (bfd) on 49 different M12 lenses ranging in focal length from f=1.7mm to f=50mm. Engagement and bfd are not standardized so the lenses vary a lot in that regard. A common bfd is 6mm or 8mm, but some are as short as 3.3mm. The flange distance (that is, the length from the last thread toward the object, back to the focal plane) which governs the length of thread engagement also varies.
The minimum bfd the Raspi can take without whittling down the stock M6 receptacle is about 3.5mm, so the M12 lens must have a longer bfd for infinity focus. You can whittle down another 2.8mm at most before you hit the filter aperture, so the lower bfd limit is only 0.7mm if you're willing to whittle. The M12 adapter accepts M12 lenses directly with maximum bfd of 11.4mm, or anything longer if you use stock M12 extender tube(s). Minimum flange distance is 11.4mm, but this covers just about all lenses. So the practical range of M12 lenses is nearly universal.
rleyden wrote:This part would simple and cheap were it not for the threads. No 3D printer that I'm aware of can directly print threads that fine.
Get an M12x0.5 tap here: http://www.use-enco.com/CGI/INSRIT?PMAKA=319-5883
Or make your own tap by grinding flutes onto a (cheap throwaway but metal) lens. You'll want a tapping guide to get the threads started straight, but if you're printing 3D I suppose you can just print yourself one of those as well, while you're at it.