Not sure if this message will make it in the thread
1. Enlarger light source.
I used to build 'bank lights'(soft boxes) for studio photography and found
that this rule applies to slide viewing light tables.
Unless the inside of the box is covered in reflective material you will lose
half your light and the light that does reach your diffused face panel will
be uneven. darker at the edges.
Best stuff is this patterned foil from Roscoe. Tinfoil or mirror will just
create spectral bright spots.
Enlarger light and lens. The primary reason for the lens focal length is
based on the standard light fall off of any lens as you leave the center
axis--something to do with the square root of 5. this is also why 90mm and
wider lenses are more even with centering filters that drop two stops in the
center.
For an enlarger light I recommend two things. I used a diffused head with
the light shinning through a piece of translucent plex. Use thicker plex,
make sure the inside of your diffusion box is white or patterned silvered.
Trans lucent plex for light boxes transmits the same amount of light
regardless of the thickness. so use the thickest plex you can afford.
Also a trick of the enlarger light manufacturers is to taper the thickness
of the diffusion near the edges. Test this and then maybe try sanding down
the edges. to gain one stop I'm pretty sure you'd halve the thickness. I'd
only work on the lamp, not the neg side of the plex and I would make sure I
had a sander and polisher to return the plex surface to a smooth original
condition.
Keep in mind too that the neg may be a particular size but the lens, and
your printing paper receives most of the light in a straight line. (This is
from Richard Feynman's Quantum Electro Dynamics) It would follow then that
the upper portion of the funnel needs to be wider than the neg. to have even
coverage.
And of course the test is to focus a neg and then remove it from the
enlarger and expose an even gray onto a sheet of paper and process it. When
I did this with my Bessler 45 I almost threw up it was so bad. I built a
better light source with high heat white paint, a little plex a surplus
quartz bulb and tuna fish and pineapple cans. BEssler condensors are only
useful as paperweights.
---William Nettles
[EMAIL PROTECTED]
Nettles Photo / Imaging Site http://www.wgn.net/~nettles
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