From: Joseph Tainter <[EMAIL PROTECTED]>
At B&H the Hoya RM 72 costs as follows:
67 mm: $ 80.95
77 mm: $283.50
Hard to figure why the 77 would be so much more. A 77 would be logical for
me. It would fit my DA 14, and with step-up rings, every other lens. It
would also fit the forthcoming DA 16-50 F2.8, which I would guess will have
a 77 mm. filter thread. But, oh, the price!
Joe
That's easy. The 77mm has to block 13% more infrared photons as the 67mm
version. It costs 350% the price of the 67mm version. There is something
inversely proportional going on. I suspect the photons at the edges are
harder to block. Makes sense to me. (or if you can afford a lens requiring
a 77mm filter you can afford a 77mm filter).
Tom C.
