I can't imagine what movements you would need to use with an SA 90/8 on 6x7 to get falloff.
Ditto. I have used this lens extensively for rail camera movements on 4x5, and never noticed any "weirdness" in my exposures on transparency film. With 6x7, I wouldn't even think to consider it an issue. If your negs are coming out underexposed, I would first look at your metering technique. The number one warning flag would be if you are using a reflected light meter. These meters require constant and diligent attention and compensation to get "ideal" exposures. The simple "point at the scene and use the exposure from the dial" method rarely results in the best possible exposure.
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