Nikon 55MM F/2B When non-TTL meter is used, At close ranges reproduction ratios greater than

When non-TTL meter is used

Reproduction

Exposure

Exposure

At close ranges (reproduction ratios greater than

ratio

factor

increase

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

1/10

1/8

1/6

1/4

1/2

1/1.8

1/1.6

1/1.4

1/1.2

1/1

in f/stops

1.2approx . 1/3

1.3approx. 1/3

1.4approx . 1/2

1.6approx . 2/3

2.3approx. 1-1/3

2.4approx. 1-1/3

2.6approx.1-1/3

2.9approx.1-1/2

3.4approx. 1-2/3

4.0approx . 2

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