Goofing around with old glop from carbon printing
dilute, nearly clear coating that covers the filter thinly
then dropping single drops of increasing density into the center from decreasing heights to form an even dispersion
How well could that crap work?
When dry the gelatin layer must be "incredibly" thin but it would have a slightly thicker central area
or would it have a slightly thicker outer area? Both?
I can't see it by eye but
Any chemical that might aid in the evenness?
I figure taking the glass out of the filter ring would help but please
someone on here said smoking a piece of glass to produce the effect might work
reverse printing the fall off onto mylar etc
just wondering which would produce the best quality easiest
I tried this as a grad ND on picture frame glass and it works well enough
not trying to reinvent the wheel
but I'm also never buying a center filter till I can take a photo that will pay for center filter