Determing exposure time
On: Sun, Apr 14, 02 04:58:44 PM
Thilo K. wrote:
|If I make some strip exposures with different exposure
times, I will still influence the final result by
increasing or waning development time until density is
about 1.0 for transmission holograms. So I canīt be sure
whether it was the wrong exposure time or the wrong
development time that was responsible for a over or
underexposure... How did you cope with that problem ?|
Tom B. - Mon, May 20, 02 04:48:47 AM It's the brightness of the finished hologram that
matters. You want to find the optimum combination
of exposure and development time. Using a relatively
flat object that fills the frame (say 4 by 5 inches),
you could expose a sheet of film as one big test strip,
exposure time increasing across the frame, then cut the
film into strips and develop each strip for different
periods. The brightest image wins. You will need to
find a way to mark the strips so you can tell which
was which afterwards - permanent marker pen ink gets
eaten by the developer - maybe a crayon or china marker,
or notching the edges? If you are using plates, you might
want to make a thin vertical developing tank so you can
lower the plate into the developer one step at a time.
Thilo K. - Mon, May 20, 02 12:43:35 PM Iīve heard this suggestion multiple times yet. But I came
to the conclusion that it canīt be the best method:
Just consider what happens if youīre using no disposable
developer for single use, if youīre using a developer with
waning quality ?
Or even if youīre using a one-time developer, what if the
temperature of it changes ?
What if your laserīs power changes due to its age ?
What if your films/plates loose momentum of their
sensitivity due to their age ?
You wonīt be able to reuse the values you get with the test
I donīt know how to do better, but I donīt think that is
the real thing. 22.214.171.124
Use this form to add your comments to the current forum entry above
| Main Index