Canon A-1 Instructions Manual page 98

AE Mechanism: Electronically controlled.
Information input by means of AE mode
selector and AT dial for full-aperture AE
metering (FD lens at "A") and stopped-
down AE metering.
Employs three LSI's with I 2 L, one
Linear LSI and one Bi-MOS IC for
light metering.
AE Mode Selection: By means of AE mode
selector. Two settings: Tv (Time value)
for shutter priority AE, Av (Aperture
value) for aperture priority AE.
Light Metering System : Through-the-lens
Central Emphasis Averaging metering by
silicon photocell located just above eye-
piece lens. Light reaches silicon photocell
after passing through fresnel lens con-
denser.
ASA Film Speed Setting: ASA6 to ASA
12800 in 1/3 step increments. With lock.
Meter Coupling Range: EV-2 (8 sec. at
f/1.4) to EV 18 (1/1000 sec. at f/16) at
ASA 100 with FD 50mm f/1.4 lens.
Exposure Compensation: ±2 f/stop range in
I/3 f/stop increments: 1/4 ·· 1/2 ·· 1 ··
2 .. 4.
Exposure Memory: EV locked in when ex-
posure memory switch is pressed. When
pressed, the shutter-speed/aperture com-
bination can be changed for the same
-98-
locked-in EV.
Exposure Preview: Viewfinder digital read-
out activated by pressing shutter button
halfway or by pressing exposure preyiew
switch or exposure memory switch.
Stop-down Lever: Foldable. Stopping-
down an FD lens is possible o_nly when
aperture ring is disengaged from "A"
mark.
Manual Override: Possible by disengaging
FD lens from "A" mark and setting AE
mode selector to Tv. Aperture manually
controlled with aperture ring, shutter
speed with AT dial.
Shutter: Cloth focal plane shutter with
four spindles. Electronically controlled,
steplessly, from 30 sec. to l /1
~00
sec.
Shock and noise damper mechanisms are
incorporated.
Shutter Speed Scale: B, 30, 15, 8, 4, 2, 1,
2, 4, 8, 15, 30, 60, 125, 250,500, 1000
plus P (with the AE mode selector at Tv).
"P" setting is for programmed AE mode.
Intermediate speeds not on the scale can-
not be set.
Aperture Scale: · 1.4 · 2 · 2.8 · 4 · 5.6 · 8 ·
11 · 16 · 22 (with the AE mode selector
at Av).
Shutter Release Button: Oversized, two-
step button with electromagnetic shutter