[Toffle]

It is surprising how easily vignetting can occur, especially if the camera is set up for a wide angle of view.

(Been there, done that, etc.)

What's amazing is that the Zero Image 45 can cover 4x5 at 25mm without vignetting. I forget the specifics of the angle of view, but it is quite extreme. That is quite a feat of design. I found out the hard way in trying to mimic their design.

Cheers,
Tom