Originally Posted by
Bob Salomon
The Heliopan is virtually identical to the Rodenstock.
Thanks for this information. I'm looking to purchase a centre filter for this lens. It's helpful to learn that the Heliopan 67/86 and the Rodenstock 67/86 are interchangeable.
Re Schneider, David A. Goldfarb says this in another thread (boldface added):
"I've compared the III to the IIIb and the difference is 1/4 stop. I use the III on my 90/8 Super-Angulon, 75/4.5 Grandagon-N and 55/4.5 Apo-Grandagon.* There are times when I'd like a stronger center filter, but it's something of a subjective thing, since even the dedicated filters don't correct 100% for falloff. If they did, they would have to be darker than most people would tolerate."
That makes it sound like both Schneider centre filters will work, but that Goldfarb may prefer the "look" of the III, which he says also has slightly less of an exposure penalty. Re his last two sentences, Schneider does say in its literature that vignetting is not fully compensated, "to avoid too long exposure times and with consideration of the exposure latitude of the film emulsions".
Link to David Goldfarb's post: https://www.largeformatphotography.i...l=1#post244210
More generally... My impression, after reading a good number of threads on the subject of centre filters, is that the main reservation is their cost. As I understand it, I'll have to stop down this lens to at least f/9 for a centre filter to work mechanically/optically. Sounds OK to me. After that, the exposure compensation appears to be about 1 1/2 stops (Bob Salomon suggests in another thread that it may be 1 1/3 stops). Maybe it's because I shoot video, where neutral density filters are a fact of life, but I'm not terribly fussed about the penalty.
If I want to add further filtration, it appears to be a matter of experimenting with Lee100 square filters (100mmx100mm), which I have, and screw-in filters that are 86mm or, with an 86mm-95mm step-up ring, 95mm in diameter. The latter interests me as an option because I have a Nikkor-W f/6.5 360mm lens that takes 95mm filters.
The trick is finding a centre filter that's in good condition optically and that I can afford
If anybody has suggestions or views that differ from what's in this post, I'd love to read them.
* Dan Fromm's Schneider table in the following article would also appear to suggest the III: Center Filters for Large Format
Bookmarks