I don't know about the precision of cos^4 part, but center spot filters are
designed to compensate for the light dropoff at the edges of wide angle
lenses. The center is neutral density (a couple stop's worth) and graduates
to clear on the edges. Large format shooters use them often for exacting
work. The most serious are matched to the specific lens. And they are
obscenely expensive :(
My Grandfather taught me to live by two rules. Rule #1: Don't tell folks
everything you know.
Matthew J. Cordery <cordery@xxxxxxxxxxxxx> wrote:
>So are center spot filters designed to compensate for cos**4 light dropoff
>wide angle lenses????
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