On light fall-off in pinhole cameras--
I've always thought (but never tried it) that you
ought to be able to make a density adjustment filter
for any pinhole camera by photographing a smooth
white, evenly-lit surface and then using the resultant
negative for subsequent shots inside the camera on
Thanks everyone who responded!
lots of good info from Guillermo snipped
If I could find out the equation, then I could make a software
center-filter to get even more useful info from the scan!
Well, I will be waiting for that software center filter.
What I was thinking was that it would
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- Original Message -
From: Soren Svensson soren.svens...@ericsson.com
My question is, how short can the focal length be for a certain negative
size?
That depends on the amount of vignetting or fall-off
Richard M. Koolish wrote:
The illumination falls off as cosine to the 4th power of the angle
from the axis.
In practical terms, the diameter of the circle is 2 1/2 the focal length of the
camera. A 2 focal length will give you a useful diameter of 5. Of course,
the
image will not
Both these factors work together to form an equation that determines how much
light reaches any point on the negative and would assume that the parameters
are: distance-from-the-center-of-the-neg, focal-length and ph-size.
The illumination falls off as cosine to the 4th power of the angle
I'm thinking about making a *really* wide-angle flat negative (not a curved
neg) ph camera (haven't decided about what material yet).
My question is, how short can the focal length be for a certain negative size?
When ph cameras have short enough focal length, the image start to get
vingetted
