Setting the asa, E. setting the asa – Canon EF User Manual
Page 43
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Setting the ASA
The ASA is a numerical rating of a film's sensitivity
to light. A higher ASA number indicates a faster film
which is more sensitive to a given amount of light; a
lower ASA number indicates a slower film which is
less sensitive to the same amount of light. The
relationship between ASA numbers is such that a
film of ASA 100 is twice as fast as one rated at ASA
50. The film manufacturer's recommended ASA
rating can be found in the data sheet packed with
the film or printed directly on the cartridge itself. To
set the ASA, lift up the ASA ring, located
underneath the rewind knob, and rotate it in either
direction until the proper number is aligned with the
white index mark. When the ring is released, it
automatically locks into position. The table below
indicates the ASA and their corresponding DIN
numbers.
• Setting the correct ASA is essential to the proper
operation of the camera, since the ASA is one of the
three bits of information (the other two are the
shutter speed setting and the brightness of the scene)
which helps the Variable Aperture AE control
determine the proper exposure.
• When changing to a film of a different ASA, do
not forget to reset the ASA ring. Otherwise, your
film will be improperly exposed.
ASA
12 •
• 25 •
• 50 •
• 100
♦
•
200
•
•
400 »
•
800
•
•
1600
•
•
3200
(16M20)
(32) (40)
(64)1801
(123)1160)
(250) (320)
(500) (650)
(1000)11250)
(2000) (25001
DIN
12 •
» 15 •
• 18 •
•
21
•
•
24
•
•
27 •
■
30
*
•
33
•
•
36
(13)1141
(16) (17)
(18) (20)
(22)
(23)
(25) (26)
(28) (29)
(31)
(32)
(34)
(331
25