Pre-exposure of film using flashing cardgreenspun.com : LUSENET : Large format photography : One Thread
I'm shooting Kodak 160NC color neg film, and have been experimenting with pre-exposure to lessen the contrast a little. I place a white card in front of the lens on location, place it on Zone II or III, and pre-expose the film before making the main exposure. Two questions:
1. Anyone have a suggestion for making sure the whole frame will be filled with the white card? I only use wide-angle lenses, so the 20x24 card sometimes misses --- obviously I can compose perfectly in the ground glass, but without an assistant I may move the card slightly before the actual exposure and not know it. Perhaps some sort of clamp affair on the rail of the Arca? Probably a larger card would do the trick, but how do I carry that around? If it's a folding card the crease might show up. I also sometimes detect some unevenness in reflectance across the card.
2. Anyone have any experience pre-exposing color negative film with a tinted card to create more warmth? Or is it just better to do this in the printing stage?
Obviously I will do more testing, but I bet you all can save me a few steps. Thanks.
-- Sandy Sorlien (firstname.lastname@example.org), November 01, 2001
Sandy: I'm not saying what you're doing will work since I've never tried it with color film. But to answer your specific question, try going to a plastics store and buy a square of white translucent plastic. You can meter your zone II pre-exposure by holding it against the meter when it is pointed the same direction as the taking lense, then hold it on the front of the taking lens for the pre- exposure. This works well for b&w and is much harder to goof up than what you are doing now. Please let us know if you are getting the benefit you want this way, I'm curious.
-- Kevin Crisp (KRCrisp@aol.com), November 01, 2001.
Ansel Adams covers this technique for both B&W and color film in one of his technical books. He suggests the use of a diffuser as Kevin mentions above. Color correction during pre-exposure would then be possible using standard camera filters. Note, however, that the color correction would only affect the lower (shadow) values in the negative. This could be a valuable technique to reduce the bluish color of shadow areas in a full-range landscape.
-- James Meckley (email@example.com), November 01, 2001.
Just move the white card closer to the lens. As long as the camera doesn't cast a shadow on the card, it will work fine. The card is not supped to be in focus.
-- Doug Paramore (Dougmary@alaweb.com), November 01, 2001.
I did it allmost at home in my studio against a white wall focus on infinity, distance to the wall about 3 feet but also only B/W. I take then 2-3 filmholders with me, with such prepered films! But you could take every wall in white or neutral grey also somewere outside! Good light, and good walls!
-- Armin Seeholzer (firstname.lastname@example.org), November 01, 2001.
Kevin has the right idea. Get two pieces of 5x5" diffuser material, the same stuff they put on top of light boxes. make a 1/4" gap between them with some fine balsa wood around the edges. The double set of duffusion provides pefect dispersion. You simply hold the diffuser product over your spot meter and take your reading, works perfect. I strongly do not reccomend shooting a grey, white or even a black card. You will be amazed at what can show up on film!
-- Bill Glickman (email@example.com), November 02, 2001.