Why no centerfilters for medium format?

[Bill Glickman]

I agree with John above.... the fall off is less than expected. I use the 43mm a lot and always leave a Heliopan EW 1 stop ND filter on. Compared to other lenses, 1 stop is not a big speed price to pay. BTW, if you conatct Mamiya in Japan, they do suggest a center filter for the 43mm.... I do not use the 50mm. My other idea of why the 43mm has less fall off than expected is the image circle size... the larger the image circle the less fall off towards the center where the image frame is. If you shoot a white wall, with and with out the ND center filter, you will notice the light fall off! BTW Howard, that 43mm is the sharpest lens I ever owned, and I have a lot of them. Some pros buy that camera strictly to use that lens, and nothing else.

[Jean-Marie Solichon]

I use a 45mm (a non-retrofocus design I guess) on my Pentax 67 and also noticed a slight but visible amount of fall-off that might need to be corrected by a 1 stop ND center filter. But this lens has a 82mm front thread then I decided to forget the filter!