Michael Heald
26-Feb-2008, 15:52
Hello! I thought I would try color paper as a negative to see how it might work with my 8x10 pinhole. I tested the paper with my 4x5 Tachihara and a 210mm Sironar N lens and an old 85A wratten gelatin filter.
The speed looks about ISO=30, and it captured about 5 stops. I tried at 1/8 sec, 1 sec, and 10 sec - all by adjusting the f-stop to hold exposure constant. The pictures get darker going from 1/8 sec, 1 sec, and 10 sec. Curious. Darker does mean more exposure in color, just as in B&W, doesn't it?
I slapped on my ND 4 (10,000x) filter and tried it at about 23 minutes. The exposure is very dark, almost obsuring the step wedge, and has a blue tint.
I'm wondering if this is evidence of a significant color shift with exposure time over 10 seconds?
I'll try my pinhole with several different exposure times and see what happens. Best regards.
Michael A. Heald
The speed looks about ISO=30, and it captured about 5 stops. I tried at 1/8 sec, 1 sec, and 10 sec - all by adjusting the f-stop to hold exposure constant. The pictures get darker going from 1/8 sec, 1 sec, and 10 sec. Curious. Darker does mean more exposure in color, just as in B&W, doesn't it?
I slapped on my ND 4 (10,000x) filter and tried it at about 23 minutes. The exposure is very dark, almost obsuring the step wedge, and has a blue tint.
I'm wondering if this is evidence of a significant color shift with exposure time over 10 seconds?
I'll try my pinhole with several different exposure times and see what happens. Best regards.
Michael A. Heald