Lens recommendations for RB67 6x8

Hi together,

I want to buy a 6x8 motor back for my RB67 Pro SD. What about the corner sharpness characteristics for the different lenses? Are the 65mm KL, 127mm KL and 210mm APO usable with this kind of back or will the pics suffer from unsharp edges or even strong vignetting/shading?

Any other experience with this combo is also highly welcome.

Many thanks ins advance.

I have the 6x8 powerback for an RB 67 - the newest type. I must have tried most of my lenses with it. Certainly 37mm fisheye (the petal hood cause slight corner cut off and lateral colour), 50 C (suspicion of gentle vignetting and lateral colour), 65 C and 90 C (no particular issues). Longer lenses too with maybe a slight reduction in frame width.
It's quite fiddly to load compared to the normal back and of course the viewfinder leaves you guessing a bit. I think your newer lenses will do just fine with it.

As I'm sure you are aware performance in the corners improves with many lenses when stopped down a little from fully open. The KL lenses were introduced to go with the SD, and the 6x8 back was introduced at the same time. It would seem like commercial suicide for Mamiya to launch a format that its lenses couldn't cover.