Use of Fujinon Center Filter on 75/6.8 Grandagon

[Brian Vuillemenot]

Hello all,

I have a 75/6.8 Grandagon that has light falloff in the corners, so I want to use a center filter. Rather than shell out a few bills for a new one, I have a center filter that I use on the 105/8 Fujinon SW lens on my G-617 camera. If I got a 58 to 67 mm step up ring, would it be effective to use this filter on the Grandagon lens? Or is each particular center filter designed to just work on one lens? The Grandagon has a smaller diameter, but also a wider angle of view- perhaps these two factors would cancel out, and the area of shading on the filter would be appropriate for this lens? Thanks for any and all advice!

[Bob Salomon]

No graduated center filters should not be used with adapter rings. To work properly they should be attached directly to the threads on the lens. You also may/maynot need a special graduated filetr. In Rodenstock's case the 35, 45 and 55mm Apo Grandagon lenses take a 67mm center filter with a 2.5x correction and the 75mm 4.5 and 90mm 6.8 Grandagon lenses take a 67mm center filter with a 1.5x correction factor. The center filetr you need is the 58mm and has a 3x correction factor.

[Gem Singer]

Hi Brian,

Are you certain that your Fuji 105SW takes a 67mm.screw-in filter? My Fuji 105SW takes a 77mm. filter. In that case, the center circular shaded area of the filter would be too large for the smaller diameter 58mm. Rodenstock f6.8 Grandagon.

[Brian Vuillemenot]

Hi Eugene,

Yes, I meant a 77 filter. I though tthat it might be too much shading.

[george jiri loun]

There is another way how you can (roughly) judge if a CF from one lens is usable for another one - take the same picture (traditionally a white wall or blue sky) with both lenses and compare their light fall off. If you see that the light fall off is the same in the proportion to the film frame on both pictures chances are that both lenses could have the same CF (questions of filter diameter apart...). This is quite a rare case but with this method you can at least see for yourself the difference in the light fall off.

[James E Galvin]

I use a center filter made for a 90 on a 65 with a step-up adapter. The adapter is very short, but still causes some loss of image circle, but since little movements are needed on a 65, it is OK.
Try it with tape or handheld, and Polaroid. The center filter need not completely correct, just good enough.