Surer-Angulon center filters

[john_galuszka]

What are the differences between a Schneider 3b center filter and a 3c? For

example, the 3c goes to a 47mm S-A, whereas the 3b is for a 90mm (both 67mm

size filters,) but is the real difference in the distribution of the graduation

center-to-edge, or the density of the filtering?

 

Can I use a 3c on a 90 mm lens and have things be close to corrected on the

edges of the negative.

 

(New filters are too expensive; used ones come up at eBay, but it seems that

only the 3c doesn't have outrageous pricing.)

[michael_briggs2]

Schneider's PDF on their Center Filters (http://www.schneiderkreuznach.com/pdf/foto/centerfilter.pdf) lists the IIIb as needing 1.5 stops compensation, and the IIIc as neeing 2 stops, so there is a small difference. It recommends the IIIc for the 47 mm f5.6 SA-XL, but has a footnote listing the IIIb as "also usable". So the filters are fairly similar. This version of the PDF doesn't list the older 90 mm f8 SA with the 67 mm filter threads.

 

An older version of the PDF did. It has the same footnote for the 47 SA-XL, but for the 90 mm f8 SA it simply recommends the IIIb without any footnote listing an alternative. So Schneider is saying that the filters are similar and reasonably interchangeable for the 47 mm lens. Whether the lack of a footnote for the 90 mm f8 SA is an omission, or because the other filter works poorly on that lens, ......