Canon FT - Aperture Ring Adjustment; Aperture Pre-Set and Depth-of-Field

Index
Pre - Set
Aperture Rin g
• The" X" index is used for synchronizing an electronic
flash unit such as the Canon Speed lite_ Although the
shutter speed at "X " is 1/ 60 sec. , it is equivalent to a
very
short exposure time during the flash of the flash
unit .
Aperture
Incoming light and depth - of-field are adjusted by turning
the pre-set aperture ring to the desired f/ stop .
• As the f/ stop value gets larger, the amount of light
reaching the film plane becomes correspondingly less.
For each f/ stop up, the light is reduced one-half . Accord-
ingly,
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 .
• Certain lenses, however, have no relation to the bright -
ness being halved between the maximum and the next
f/
stops on the pre - set aperture ring.
• The pre- set aperture ring can also be set between two
f/ stop s.
• The ratio between the aperture
exposure, using f/2 as the basis, is
f/s
top :
1.2 1.4 1.8 2 2.8 3.5 4 5 .6 8
Exposure
RaUo:
and the amount of
as follows :
11 16 22
3 2 1.25 1 1/2 1/3 1/4 1/8 1/ 16 1/ 32 1/ 64 1/ 128
Pre-Setting Aperture and Checking Depth-of-
Field
Lens with A-M Ring
1
Pre - Setting of Apertu r e: Set the A-M ring at "A " .
Then set the desired f/ stop on the pre-set aperture
13