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The Exposure
Meter System
The measuring
principle
The photoelectric
exposure
meter in the TTL Attachment
works ac-
cording to the principle of partially integral measuring,
i. e., meas-
uring takes
place integrally
within the area,
25 mm in diameter
(16), as marked in the viewfinder. This arrangement
has the ad-
vantage
that special allowance
is made for important
sections of
the image.
The exposure
meter system is constructed
in such manner that the
light required
for measuring
is taken
from the image-erecting
surface
of the pentaprism
and conducted
to the CdS photo re-
sistor.
Power source
is a mercury-oxide
battery
Mallory PX 13.
The metering
process is quick and simple. The meter needle
has
only to be moved to coincide
with a fixed mark by rotation
of
control knob (3).
Movement of the meter needle may be watched either through the
ocular, in the section (15) next to the viewfinder, or in the window
(2) on the top of the TTL Attachment.
There are two possibilities
of interna I measuring
with the TTL
Attachment:
a) measuring
with lens at full aperture,
b) measuring
with lens at taking aperture.
Scales for film speed, f stops, and exposure speed
On knob (3) are the two scales indicating
the film speeds.
Ring
(4) bears the exposure
speed
numbers
and the index mark (6)
for setting the film speeds. The separate
ring (7) below knob (3)
shows the numbers and the index mark 8.
Film speed scales
Control knob (3) is provided with two scales for setting the film
speeds in DIN and ASA values. Lift the exposure speed ring (4) in
axial
direction
and
move it to set the speed
of the negative
material
in the camera.
Ring (4) clicks in at every DIN value, also
at the intermediate
stops between the values on the scales.
All the values listed in the table below are adjustable
on the TTL
Attachment.
The film speed values printed
in special
type indicate
the num-
bers marked on the scales.
9
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