6x7 negatives (e.g. from a Mamiya RZ 67) measure 56mm on their short side.
Capturing all of that width with your GFX will get you a 1:1.7 (=0.59) imaging ratio.
Please take into account that the GFX has a 3x4 or 6x8 aspect ratio, so you’ll sacrifice at least 1/8 of sensor pixels or some of the negative’s area.
Considering an imaging ratio of 1.7 (as seen from an enlarger point of view) and data given in the provided brochure, your best bets are the 70mm and the 120mm Apo-Rodagon-D lenses…but both of these have relatively low (but flat) MTF curves compared to e.g the ones of the Apo-Rodagon(-N) lenses…BUT the curves are measured at different imaging ratios and can therefore not be compared. Also check the effort and $$ to adapt the lens to your camera.
Before investing in those lenses, I’d try to test them first and decide based on what you find.
I also propose you check out https://www.closeuphotography.com.
Most contributors here use main brand lenses but some use gear from e.g. Schneider Kreuznach and others. At the end (or preferably before you buy) you need to answer the following:
How large do I need or want to print?
Will those images sit in my computer and be projected or looked at on the TV occasionally?
With respect you’re misinterpreting the information in the brochure. For this use, i.e. copying film, consider ‘6x7cms’ to be the maximum size of the sensor, see the note on page 59 of that brochure “The given scale ranges refer to projection; when the lenses are used as taking lenses the respective reciprocal values apply.”
So your GFX will be fine with the 75mm Apo-Rodagon D (Duplicating) lens, but which one, the 1x or the 2x? The Apo-Rodagon N range of lenses are enlarging lenses so at the outside of their designated range. Might the 120mm Apo-Rodagon D be better on GFX? I don’t know but from the specs you shouldn’t need to go to the 120mm.
The magnification required to copy 6x7 negatives (say 67 x 56mm frame area) on to a 44 x 33 mm sensor is 33/56 or 0.59x. The ‘1x’ is a symmetrical lens and so at its best at 1:1, the ‘2x’ is optimised for 0.5x so almost perfect for your requirements. That said others recommend more exotic lenses such as SK Apo-Digitars etc. so it is worth roaming through this forum and also particularly the Facebook forum “Digitizing film with a digital camera” for other suggestions. Also there are ideas as to what you might need to mount them to your GFX, generally MF bellows or possibly 65mm extension rings, both adapted to take the L39 thread of the lenses.
“If you wish to use a less painful DoF, look out for the Rodenstock APO Rodagon 75mm 2x f/4.5. I strongly advice to go for the 2x version here, as the 1x version covers only up to 6x6 MF negatives while the 2x version has a super huge image circle and performs better in magnifications other than 1:1.”
Note that it seems that Schneider Kreuznach seem to ‘re-badge’ older lenses for the digital age so that you may or may not find that they are the same though named differently. Information is hard to get, are there subtle differences nonetheless? Who knows?
Thank you to everyone that has helped me out, i will be going with the 75mm 4.5 2x as i believe is the best balance. I will be posting results as soon as i get to test it.
Just for reference here is another Rodenstock (Linos) page where detailed information about the Apo-Rodagon D lenses can be downloaded. The 120mm f5.6 is described as a ‘2x’ here and references to ‘Maximum film format’ have been removed to be replaced by image circle dimensions. I don’t know but I suspect that the image circle is expressed for the lens focused at infinity and would be much larger at the useable magnification range. In any case the image circle in all cases is much larger than the 55mm diagonal of the GFX sensor. The first brochure that you linked to has the magnification range of the 120mm as ‘0.5x to 3x’, much greater than the ranges of the 75mm 1x or 2x. I think this is a mistake and includes the magnification when the lens is reversed. In the second brochure it is listed as ‘0.33x to 0.8’, so very similar to the 75mm 2x. Confusing or what?
Well I think it will be fine, but as you say I’ve never tried it on GFX. It’s very well tested on Full Frame though. I think people have simply misunderstood the information given about film formats in that first brochure. Would the 120mm be better, say regarding vignetting, I just don’t know. I’m a bit short of time but I could test it on Full Frame and extrapolate to GFX as my Nikon PB-4 bellows has lateral shift at the lens stage. I think you should get it though.
Jim Kasson tested the 75mm f4 Apo-Rodagon 1x at 1:1 on a GFX, it performed very well. That lens has a slightly smaller image circle then the ‘2x’, hence the recommendation for 6x6 film format copy camera in the earlier brochure. That lens didn’t perform well at 1:2 and he doesn’t seem to have tried a ‘2x’ because that would have done. He has very high standards (and deep pockets).