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When non-TTL meter is used
At close ranges (reproduction ratios greater than
1:10), the amount of light reaching the film decreases
as the lens-to-film distance increases. When non-TTL
measurement is used for this range, the result is under-
exposed photographs unless compensation has been
made for this decrease. (When the Micro-Nikkor 55mm
f/2.8 lens is used with the Photomic or Nikkormat
TTL meter it is not necessary to make compensations,
since the meter is designed to give an accurate reading
of the amount of light reaching the film.)
The table on the right gives the exposure factors (com-
pensation values) with exposure increase in f/stops for
non-TTL exposure measurement at reproduction
ratios greater than 1:10.
To calculate the necessary corrections in shutter
speed rather than in aperture value, multiply a given
exposure factor by the exposure time. For instance,
if the normal exposure at a 1:1 reproduction ratio is
1 /8 second, the correct shutter speed is 1 /8 x 4 = 1/2
second.
The following formula is used to calculate the expo-
sure factor: Exposure factor = (1 + R)
2
where R = Reproduction ratio
Reproduction
ratio
1/10
1/8
1/6
1/4
1/2
1/1.8
1/1.6
1/1.4
1/1.2
1/1
Exposure
factor
1.2
1.3
1.4
1.6
2.3
2.4
2.6
2.9
3.4
4.0
Exposure
increase
in f/stops
a p p r o x . 1 / 3
approx. 1/3
a p p r o x . 1 / 2
a p p r o x . 2 / 3
approx. 1-1/3
approx. 1-1/3
a p p r o x . 1 - 1 / 3
a p p r o x . 1 - 1 / 2
approx. 1-2/3
a p p r o x . 2
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