New Raspi HQCam - a question of (white) balance

@patcooper: have a look here to see my own setup, using a Schneider Componon-S 50mm lens.

Basically, as the size of the HQ cam sensor is nearly identical to the size of a slightly over-scanned Super-8 frame, you want to realize a 1:1 optical setup. Now, this is a very well-known thing. If you have a lens with focal length f, you place the object of desire (the Super-8 frame) at a distance d = 2 x f. Similar, in order to get a sharp picture, your camera sensor will need be placed the same distance d away from the lens. That’s all. So adding everything together, you end up with the distance between Super-8 frame and camera sensor being 4 x f and the lens placed midway between Super-8 frame and camera sensor.

Strictly speaking, the above is only valid for thin lenses - real lenses have different front and back focal distances which would need to be taken into account.

You can realize the appropriate distances with extension tubes, have a look at @jankaiser’s post for an example, or you can use 3D-printed extension tubes as well (my own approach, see here - stl-file at the bottom of this post).

For your 16mm lens, things might become a little bit crowded, as the approximate distance between lens and Super-8 frame would be of the order of 3 cm or so. Here, the exact locations of the front and back focal distances would be good to know because the difference between them will be of the order of these 3 cm - however, I do not have this information available for the 16 mm lens.

Besides, note that using a lens designed for imaging objects from about 1m to infinity is not the best choice for using it in a 1:1 macro imaging situation. That is why reverse mounting of a standard photographic lens is often used for macro work. The 1:1 imaging situation is however even more challenging - reverse mounting a lens would not improve the design mismatch between the operating distances the lens is calculated for vs the distances the lens is actually operated.