Film color correction filters for reciprocity failure
Greetings. I'm shooting Fuji FP-100C (color instant) film in a pinhole camera I made, and not surprisingly I need very long exposures.
according to the Fuji datasheet for the film, I should use 7.5Y and 12.5R color correction filters for exposures over 10 seconds, but I can't seem to find anything like this online. Can't find shoot through filters for cameras or just gels for lights.
I actually have some Roscoe ColorCal gels for lights/strobes, but theyre all in increments of 15, 30, 60 etc which won't work obviously.
Can anyone tell me where to get the filters I need? I'm willing to try lighting gels in front of my "lens" just to see how badly they affect image quality compared to actual shoot-through filters.
You can break R into 12.5 Y and 12.5 M and add it to 7.5Y
So 20Y and 12.5M
Thinking to myself, for pinhole purposes, 15M and 30Y would probably be close enough.
OK here is another idea... alter the relative brightness or distance of different strobes or lights with whatever gels you find that are close.
Example you find only 20Y and 15M ... put one on each of two different but equal brightness lamps... Move closer with the 15M and it will act more like 12.5M.
Gel filters are becoming hard to find and expensive now that most people are using digital color correction. Kodak has handed their filter business over to Tiffen.
Go to Amazon.com for Calumet/Lee filters or to Calumet Photo or BHphotovideo.
At Amazon search for something like "cc010 yellow filter"
At Calumet search for "polyester filter" (Calumet search is horrible)
At B&H search for "cc filter" and then narrow your search
This will get you as close as possible to what you want. Polyester seems to have replaced gels in a lot of cases, and they are much less expensive.
Don't worry if you're off by +/- 2.5 CC. Your lighting will vary far more than that unless you're shooting under tightly controlled studio lighting, and many people can't see or won't notice that much variation.
With a pinhole camera, dust on filters is highly likely to show regardless of where you place them. You might want to put them inside the camera spaced back from the pinhole, as dust right at the pinhole could affect overall exposure to a significant degree.
Hmm, last post didn't take?
I tried 15 and 30 and that was too much.
I also tried 15 and 30 over a light source (well, one) and that was about the same. Two equal light sources ought to be similar though.
Finally I thought of this: Assuming I have an exposure that's long enough (not hard at ISO 100) I could just leave the 15 and 30 on for half of the exposure maybe. I'm not sure how the reciprocity curve goes, so it might not be exactly half exposure time but I'm betting that some fraction of the exposure with the too-dense filters would work.
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