Hello,

I have tried searching the forum and the internet, altough a lot of information can be found about the Grandagon-N it is hard to find information about the plain Grandagon (non-N).
When shooting 4x5 I close the lens down to f22. But, I want to start using the lens with a 6x9 back to hopefully be able to shorten my exposure times. I shoot most of my work at night and run exposure times from 30 to 60 minutes most of the time, sometimes this is still not long enough so I am hoping to be able to use f16 on 6x9 and shorten my exposures in some situations a bit.
I have seen on the Rodenstock site that the working aperture for the Grandagon-N 90mm 6.8 is stated at f22-f32, but I assume that this is to make sure the coverage is adequate. If I were to shoot for 6x9 at f16 the coverage would be more than okay, my question is: would the sharpness at this aperture be okay, or is this lens sharpest at f22-f32 and is f16 to soft to use the 6x9 negatives? I want to make analogue c-prints, approx 100cm wide with the negatives, I know 4x5 will be sharper and finer grained, but this is just for those cases where the exposure times end up being way to long.

Thank you for you answers in advance.