To be used for Stereo Ninja, a camera must be

• compatible with the Raspberry Pi
• have adjustable focus, or rather a interchangeable lens
• small form factor

The small form factor is important to archive a good stereoscopic effect. The distance between the cameras should correlate with the distance between the eyes. We use camera with a PCB footprint of only 25x24mm, but even when mounting these cameras closely next to each other, you get a slightly exaggerated 3D effect. This is fine (and might even help with working with the microscope) but a larger distance is not helpful and is not comfortable for the eyes.

TL;DR: Use the Waveshare RPi camera model G

Raspi Cam v1 (OV5647, 5MP)

For now, we are using Waveshare cameras with Raspi Cam v1 compatibility. They have a PCB size of 25x24mm.

There a several variants, the following fit the specs:

Model H should be fine as well, but it comes with additional IR lights mounted on the sides of the PCB.

If using IR variants makes sense is unclear, we haven't test it.

As the lens will be exchanged anyway, you can go for the cheapest model, at the moment this is model G.

Raspi Cam v2 (IMX219, 8MP)

The official v2 cams do not have adjustable focus and the lens cannot be changed to another one, so they do not fit our requirements unfortunately.

Because the they a higher resolution they would be interesting however. One possibility would be to take a standard v2 camera PCB and swap out the camera with this one (same sensor, but interchangeable lens).  Still needs testing. 

Raspi HQ Cam (IMX447, 12MP)

The Raspi HQ cam certainly would be interesting to use. It has a better resolution and also a much larger sensor (6.3×4.7mm compared to 3.8×2.7mm with the v1 cam). Unfortunately it is a lot more expensive und also a lot larger. With 38x38mm the PCB footprint doesn't allow the cameras to be as close together as they would need to be. We could mount them further away and archive the same angle between the two camera, but we did not test that (yet).