Ha Ha! Good One! Yup, might just be a bit more than my Kipon Shift adapter
Any idea what lens would provide that much shift (without the edges falling completely apart) in the 45mm - 50mm focal length? I could probably make a "mini" version for my purposes, if such a lens existed....
Thanks again!
Believe it or not, a new Kipon Tilt-Shift adapter from B&H for Pentax 645 to Fuji GFX costs $628, but you can buy a good condition used Toyo VX23D for $800-900 if you watch the listings. There are two nice ones in that price range on eBay right now. You have to build, or have someone build, boards to mount the camera and the lenses you're using, but it's neither hard nor expensive.
https://www.robdeloephotography.com/Pages/Toyo-VX23D-and-Fuji-GFX-50R
With any adapter on a Fuji GFX camera -- whether my VX23D, a Cambo Actus, or a Kipon/Fotodiox solution -- wide angle lenses are the problem. In a nutshell, technical camera lenses wider than 60mm are generally out. You're going to have to use retrofocus designs (basically, medium format lenses designed for SLR-type cameras).
On my VX23D, I have used a 60mm wide angle enlarging lens, which gives a clean 10mm of shift (more is possible but starts to get dodgy at the edges). That kind of lenses has to be focused with a bellows or rail. A Cambo Actus, and my VX23D, allow for that kind of focus -- you move the front or rear standard back and forth to focus. You can't use that kind of lens on a Kipon or Fotodiox tilt-shift adapter because there's no way to focus even if you can mount it (unless you rig up some kind of focusing helical, but that's awkward, and there are better options).
In the 45mm to 50mm focal length, with medium format lenses that have focus mechanisms, you have a few choices. Your main choices come down to Hasselblad (which covers 6x6 film), Pentax 645, Pentax 67, and Mamiya 645. The biggest image circle and best image quality is going to be the 3rd generation (latest version) of the SMC Pentax 67 55mm f/4 lens. It's this one:
https://www.pentaxforums.com/lensreviews/SMC-Pentax-67-55mm-F4-Lens.html (But see below for an alternative that has an image circle that is almost as large, and has excellent image quality.)
The optics on the 3rd generation Pentax 67 55mm lenses are superb, and the image circle was designed to cover 6x7 film. The portion of the film that is image on my 6x7 negatives is 56mm x 69mm, which means the image circle has to be 88.9mm to just cover that -- so call it 90mm to be conservative. The actual area of illumination will be larger, but image quality beyond 90mm is likely to be poor. Here's what a 20mm shift on a 90mm image circle looks like. As you can see, that's pushing you out past the edges of the image circle.
If 55mm is too long, Pentax made a 45mm lens for the 6x7 system. I've used it on a GFX. Where the 55mm is "excellent", the 45m is "Very good". It's definitely not as sharp, but the colours are nice. It shows barrel distortion, but it's simple and easily corrected. I sold my copy because the 45mm end of the SMC Pentax-A 645 45-85mm zoom lens is noticeably better. The tradeoff is that Pentax 645 lenses as a rule have a much smaller image circle than Pentax 67 lenses because they only need to cover a much smaller area of film.
But... here's where we benefit from the zoom lens design. Many zoom lenses have an interesting property: the image circle is "tight" to the film or sensor size at the wide end, increases (sometimes a lot) in the middle of the zoom range, and then decreases back towards the minimum size needed to cover the film/sensor at the long end.
The SMC Pentax-A 645 45-85mm zoom is "very tight" at 45mm, very large at 60mm, and "moderately tight" at 85mm. In practical terms, with this lens I can get 10mm of shift along the long side of the frame at 45mm, and easily 20mm at 60mm. In fact, I've made test pictures with 25mm of shift along the long side of the frame at 60mm where all but the very corner of the frame was usable. That means the image circle is nearly 90mm at the 60mm mark on the lens. It won't be 90mm at the 50mm mark you need, but it will be larger than it is at 45mm.
Not only that, but this is an extremely good lens -- easily as good (and better in some cases) than all the 645 prime lenses in its focal range that have aperture rings. In a long post on DPReview, I compared the 63mm point on this old zoom to the modern GF 63mm f/2.8 lens, and showed that the old zoom easily holds its own.
https://www.dpreview.com/forums/post/63644793
If you decide to get one of these, I would recommend the FA (autofocus) version. It still has the aperture ring, the optics are identical to the manual A version, and manual focus is fine (not as easy as on the A version, but still very good). The reason I recommend this is the front element doesn't rotate when you focus, like it does on the A version. If you never use polarizing filters, that's not an issue. But I use a CPL a lot, and it's a pain in the butt to have the front rotate; I have to constantly re-adjust my CPL as I change focus in a scene.
