SIMPLE IS AS SIMPLE DOES
Even with careful exposure, you might notice that your results are often
unexpected, inconsistent, or even undesireable. You might suspect the
development of the film, even if you don't do the processing yourself.
Just because a professional or an expensive machine does the processing
does not mean that you're getting the best results. Fortunately, there
are a few simple tests that you can make to assure that your film exposure
matches the processing technique of the shop that handles your film. Since
this is a simplified approach, the only pieces of testing equipment you will
need is a Kodak grey card and an inexpensive filter -- a Kodak ND 0.1 (neutral
density) 3x3 inch gelatin filter. These are available through most
camera shops, and are useful for more things than just this test. The
tests are relatively simple, but you may find that you need to repeat them
several times -- depending on your situation.
1. Since the processing is fixed by your lab, you can make a test to get
the best exposure for their processing methods and your equipment.
A. Set up the grey card in a sunny spot with no reflections or shadows falling
on it. Set the lens at infinity but move close enough so that the grey
card fills the frame of the viewfinder. Use whatever metering method
you like, at whatever ISO film speed you normally use and make an exposure
of the card.
B. Now cover the lens with a lens cap or opaque cloth and make another exposure.
This will produce a clear section on the negative right next to the
grey card exposure.
C. Expose the remainder of the film normally. This keeps your test
exposures down to a minimum.
D. When you are done with the roll, have it processed normally.
E. When the negatives (and prints) are returned, find the negatives of your
two test exposures.
F. Cut the gelatin filter into nine one-inch squares.
G. Stack seven of the filter squares together -- this stack will create a
0.7 ND filter.
H. Place the filter stack under the "clear" exposure, right next to the grey
I. Hold up the negative with the filter stack and look through it. The
densities of the grey card exposure and the "clear" exposure/filter stack
should appear the same. This will be easier to do if you place a white
piece of paper under the negative or hold the negatives up in front of a
J. If the grey card exposure is darker than the "clear" exposure with the
filters, you are over-exposing your film (for the lab's processing). On
the next roll of film increase the ISO film speed one notch and retest.
For example, if your original roll of film was exposed at ISO 100,
shoot the next roll at ISO 125. Keep re-testing until the grey card
exposure matches the "clear" exposure/filter stack.
K. If the grey card exposure is lighter than the "clear" exposure with the
filters, you are under-exposing your film (for the lab's processing). On
the next roll of film decrease the ISO film speed one notch and retest.
For example, if you original roll of film was exposed at ISO 100, shoot
the next roll at ISO 80. Keep re-testing until the grey card exposure
matches the "clear" exposure/filter stack.
L. Even when you get a match, it's a good idea to re-run the test every once
in a while. You'll actually be testing the consistency of the lab.
Some are more consistent than others.
2. You'll need to rerun this test, for each film that you use, or if
you change processing labs.
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