In article <32091363.A27@uiowa.edu>, mark-s-peterson@uiowa.edu says...

>I've just purchased a 24mm lens (Nikkor 24mm f2.8), and
>having just completed the "brickwall" test with it this
>week, I see that it exhibits about .5-stop falloff at
>the edges at f/22 at infinity focus (falloff is less
>at f/16 at infinity, and not noticeable at larger
>apertures).
>
>I am familiar with what causes falloff and methods of
>calculating just how much there might be. Might I ask
>those of you familiar with this phenomenon with this lens
>(or similar ones) to comment on how you DEAL with the
>falloff? Obviously, one of the primary uses for a 24mm
>is to shoot sweeping landscapes, taking advantage of the
>tremendous f/22 DOF. But, also obviously, this is going
>to result in noticeable falloff if a big blue sky is
>included in the composition. This may be a ridiculous
>question given the physical properties of the lens, but:
>Is there any way to minimize this effect?

Yes - remove the offending shade and filter! ;-) Actually,
what you observed is the reverse of what I would expect
using the lens alone - generally, illumination becomes
more even at the smaller stops (though the 24mm Nikkor is
very even in illumination, and you should not see corner
darkening at all even on contrasty slide film at f5.6
and smaller apertures).
Hope This Helps