>
> Recently I've been working a lot with Ilford MG IV Fiber Matte paper. I
did
> a series of tests and determined that, for a 7 inch (178 mm) focal length
> camera with a .4 mm aperture, the proper exposure in full sun is 70
seconds.
I use the same paper for my pinhole negatives, with similar focal length and
aperture (150 mm, 0.4 hole), and I find the same exposures.
But the sensitivity is strongly different, regarding the colour temperature
of the ambient light. Papers are very sensitive in blue light, far less in
yellow, quite blind in green, and totally unsensitive in red light.
With a bright sun and pretty blue sky, exposure time is less than 60
seconds. With a low sun and yellowish ambient light, exposure time must be
far longer, 15 minutes for instance, even if light-meter says only the loss
of one diaphragm.
JMB
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Received on Wed Mar 17 18:49:58 2004
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