Center Filters and Magenta Filters
Hi, apologies for another newbie thread, but I want to learn what I'm doing a little before blowing all my money on a LF setup.
I'm basically just wondering for what focal lengths I'll need center filters on 4X5 if I want next to zero (a half stop or less) fall-off with limited lens movements and moderate lens movements at longer (≈200mm) focal lengths. I'm extremely particular about this, especially since I shoot slides and I just hate fall-off unless it's very minor (half stop or less at most).
I saw this show a few years ago:
and read in the artist's statement that he doesn't use filters. It seems his minute-long exposures and exclusive use of velvia would require center filters and magenta filters (to correct for reciprocity error). Or am I missing something?
I'm assuming 90mm and wider (on 4x5) should use center filters? But I know they make filters for longer lenses, too; is that just if you're using 5x7 or something or doing architectural photography and need ridiculous amounts of lens movement? Thanks! I'd rather have a good lens with even light dispersal than a "great" lens and bad fall-off, so I want to know how to invest.
Last edited by Policar; 08-30-2010 at 01:22 PM. Click to view previous post history.
First off, I'm a newb just like you, so take my comments with a grain of salt.
However, I would consider and contemplate the following statement by Mr. Turner:
"As I gradually moved from painting to photography in my twenties ..."
Note I've underlined the word "painting." IMHO - Turner, based on his experience as a painter probably has a very high-level understanding of color theory; so figure that into what he may be doing post-process.
As far as center filters: Well, depends on what you're shooting. A 90mm Super-Angulon XL, depending on subject matter, e.g. architecture, and your personal tastes may require a center filter, then maybe not. Some LF photographers don't use them, some do.
When it comes to Magenta filters: Since these are color compensating filters, it would depend on the film used and quality of light. Are you attempting to adjust/correct color contrast, density, etc.
Just something to think about ...
I think that lenses above 90mm on 4x5" should produce minimal or no noticable light fall off.
As for compensating for reciprocity in Velvia, I'm sure the majority of those pictures were taken w/ shutter speeds less than 1 second, and frankly color shifts at that point would probably be minimal. Seeing as those are online, post production color balance would have been effortless. Only when we're working w/ 100% analog work flows would such a minute imbalance of color be a concern, IMHO.
I'd say get some gear and start shooting! You'll soon discover if you really need one or not.
I should probably just start shooting but it will take a little while to get all the gear together. I wanted to make sure first that if I needed a center filter it would work for all my lenses and not be too big. The big ones are $500 and have huge front threads. Fall off bugs me a lot for some reason, even though I usually end up adding it in photoshop, which is weird. On velvia a tiny bit of fall off is very noticeable so I guess I just like to be able to control it.
Velvia 50 turns toward green and requires a magenta filter with long exposures per fuji's specifications. I'm certain some of the shots on that site have exposure times approaching a minute, though most are likely much, much shorter. Maybe it's just something he corrected digitally.
How much of what kind of filtration you want is best determined by testing. Get the gear and see what happens. Set yourself up in a situation that allows you to test reciprocity-related color shifts at various exposure lengths. Then figure how much corrective filtration is required for each exposure.
Falloff at the edges of a frame will be more noticeable the contrastier your film is. Velvia is very contrasty. It will show more falloff. Fuji Astia gives excellent color with much less contrast. You can always boost the contrast using the type of equipment forbidden to discuss on this forum.
I've never used a center filter with my 90mm Super Angulon, and I don't notice the falloff. YMMV. Buying one filter for all your wide angle lenses probably won't work. Each lens has a filter with a gradation specific to it. The bigger the filter diameter, the larger the gradated area. The filter for a 110 XL might cover the entire front lens of a 90mm Super Angulon. See how it all works before dropping a bundle of cash on an expensive filter.
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Thanks, Peter. It appears many LF lenses have 67mm threads and are compatible with or partially corrected by the Schneider IIIb filter, and I anticipate based on photos I've seen that for anything wider than 90mm I'll absolutely want a filter. But I can't tell for sure without trying. Maybe I will look for wide angle lenses with 67mm threads. I know it's silly to speculate, but I'd rather get the right gear for my needs the first time around.