Canon TX - Page 14

equivalent to avery short exposure time during the flash
of the flash unit.
Aperture
The aperture is set by turning the preset aperture ring
to the desired f/stop.
= As the f/stop number gets larger, the amount of
light reaching the film plane becomes correspondingly
less. For each f/stop up, the light is reduced one-half.
Accordingly, when the aperture is increased by one
f/stop, the exposure is doubled, and when it is increased
by two f/stops the exposure is quadrupled.
= The maximum aperture of a lens may not be one
included in the international standard series. If it is not,
the second f/stop will not designate an aperture one-half
as large as the first f/stop.
= The ratio between the aperture and the amount of ex-
posure, using f/2 as the basis, is as follows:
f/stop:
121418 2 2.8 3.9 4 5.6 8 11 16 22
Exposure Ratio:
3 21.25 1 1/2 1/3 1/4 1/8 1/16 1/32 1/64 1/128
= The preset aperture ring can also be set between two
f/stops.
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Index
Preset
Aperture Ring