Center Filter For 75mm & 90mm

[Sam Clarke]

Does anyone know if the Rodenstock center filter for the 90mm 6.8 Grandagon will work properly with a Schnieder 75mm Super-Angulon 5.6? The specifications for the Rodenstock filter indicate that it can be used on the Rodenstock 75mm 4.5 lens. I am about to bit the bullet and buy one of these hideously expensive filters. I was initially going to get the Schnieder filter for the 75mm but noticed the Rodenstock alternative and was hoping to cover both lenses with a single filter. Both lenses have 67mm threads so I know the filter will fit. I'm simply not sure if the technical differences between the two 75mm lenses are sufficient to compromise the effectiveness of the Rodenstock filter when used on the Schnieder lens.

[Bob Salomon]

Rodenstock makes two 67mm center filters One for the Apo Grandagon series and one for the 90 6.8 and 75 4.5. The difference in the filters is the center density. What is the center density of the Schneider? Then you would know if either of the Rodenstock or the Heliopan CF would work properly.

[Ole Tjugen]

The Schneider lens takes a "III", 1.5 stops center density: http://www.schneideroptics.com/pdfs/...LensCharts.pdf

Note that there is also a "IIIb" and a "IIIc" - the difference between "III" and "IIIb" is in the gradient.

[Sam Clarke]

Bob & Ole;

Thanks very much for the quick help.

I looked at the specs for both filters and find they both have 1.5 stop center density. My conclusion is that the single filter will work on both lenses.

Thanks, again.

Sam

[JPlomley]

Sam, I have been using my 75/4.5 Grandagon-N without a CF shooting chrome film and I find that the very slight fall off actually helps to draw the viewer into the image. Check out Dykinga's book as well. He does not use a CF on his 75/5.6 SA for the same reason. On ultra-wides such as the 47/55/58 it is essential, but I'm not convinced it is required for 75mm. I also have the 90/4.5 Grandagon-N and definately have never required a CF for this optic.

[Ole Tjugen]

On the other hand, I have sometimes missed not having a center filter for the 90/8 Super Angulon. On 13x18cm chrome film...