I've recently acquired a Viselex Rhinocam and stuck a Pentax 645 75mm 2.8 on it, to see whether I like it or not. I know there are a few people on the LuLa forums who use one.
What's troubling me is that I seem to get getting inconsistent exposure between shots, but I have my X-T10 completely in manual mode. Fixed exposure of 1 s, fixed ISO of 200, fixed WB (shooting RAW+JPG). I'm in S mode, so no bracketing. The shots were taken indoors a second or two apart under constant illumination, so it's not the light changing. With a long exposure like 1 s, it can't be lights strobing.
I've composited two of the shots together in PS so you can see how different they are. Not the full res, just enough to show the effect. These are RAWs SOOC and into PS via LR, but much the same is seen with JPGs. I've used the Adobe Standard profile.
If you don't know how the Rhinocam works, it's a stitching device where the camera moves and the lens remains still. The only thing you really need to know here is that it seems impossible that the lens can be responsible for these issues. It's not talking to the camera, and its aperture is fixed between shots. Any lens vignetting should be a smooth effect, not quantised between shots. I don't see how it can be the issue.
I also thought about the mechanism somehow producing flare in varying amounts as the body moves across the lens, but I can't see any sign of it.
Of course, the exposure difference can be adjusted for by stitching programs, but I'd love to know where it's arising.
Any ideas? Anyone seen this before? Thanks in advance...