I have one of the two RB67 lenses that I've ordered, both 77mm filter size, so I started a search for the filters. I was surprised to find so few and the filter ads were geared toward d i g i t a l. DuH I guess.
Where is the best place to get the best price on a K1, K2, R25, you know the reds, yellow, greens? Some where there are photo stores that are or have closed and have drawers of the old fashioned filters for the old fashioned cameras that take the old black and white film.
Oh to be a mouse in such a store!