In article <1995Dec27.154430@acad.drake.edu>, pk6811s@acad.drake.edu says... (..about asymmetrical aperture at small stops)
>If it is bad enough to shift the center of the aperture off the lens
>axis, you may begin to notice a darkening in one direction of the pics,
>or that your pics are not centered.

Uh-uh! Sorry, don't think so... Since we are talking about an aperture at small stops, the asymmetry would need to extend to the edge of the lens to cause cutoff, and the area would be so incorrectly overlarge
that any cutoff would help. Also, the diaphram position has nothing
to do with image placement, but could affect sharpness somewhat, I
guess, if it was very far off center. The lens itself would need
to be decentered in the mount to show the effects you describe.
Hope this helps.