Minolta XE - 10. Explanation of Light Measuring Principle and Circuits; A. Summary; Light Measuring Systems; Memory Systems

10.
Explanation
of
Light
Measuring
Principle
and
° °
Circuits
Sensitivity ;
Override
of
film
Diaphragm
|
Addition
Addition
ae Brightness
Addition I at object
Indication
Memory switch
Memory
| Logarithmic Extension |
Manual = [ A
Resistor M ?
| First switching |
checker
|
Second
switching
|
L
A. Summary
@ Light Measuring Systems
The
measurement
of
light
is
roughly
divided
into
2
systems-the
TTL
light
measuring
system
as
represented
by
X-1
(XM
and
XK)
and
the
outer
light
measuring
system
by
Hi-MATIC
E.
In
the
case
of
the
TTL
measuring
system,
automatic
exposure
is
possible
only
with
the
time
set
circuit
comprising
the
CdS
and
the
condenser
and
with
the
switching
circuit.
The
reason
is
that
the
resistance
value
does
not
change
or
block
light
to
the
CdS.
In
the
case
of
a
single
reflex
camera
of
the
TTL
measuring
system,
its
circuits,
if
const-
ructed
like
those
of
the
outer
light
measuring
system,
won’t
be
able
to
achieve
automatic
exposure,
because
its
operation
(automatic
aperture
setting
and
mirror
operation)
will
change
or
block
light
to
the
CdS.
Therefore,
it
is
necessary
to
memorize
the
results
of
the
TTL
measurement
immediately
before
the
release
of
the
shutter
so
that
the
effects
of
the
auto-
matic
aperture
setting
and
the
mirror
operation
may
be
prevented.
@Memory Systems
A
variety
of
memory
systems
are
conceivable.
A
system
of
charging
the
condenser
with
the
results
of
the
light
measurement
and
memorizing
the
charged
voltage
is
adopted
for
XE
as
well
as
for
X-1.
In
addition
to
this
memory
system,
XE
has
a
more
complicated
construction
and
needs
more
accurate
components
and
adjustments
than
cameras
with
lens
shutters
of
the
electronic
control
type
such
as
Hi-MATIC
E
and
F,
because
it
has
wide
ranges
of
the
light
measure-
ment
and
the
film
sensitivity,
and
because
it
requires,the
interchangeability
of
various
lenses
and
attachments.
@
Automatic
Exposure
Control
Systems
The
automatic
exposure
control
system
for
XE
will
be
explained
according
to
the
block
diagram.
a.
Light
Measuring
System
The
automatic
exposure
control
system
for
XE
is
the
same
as
that
for
E-1.
It
is
designed
to
obtain
adequate
exposure
by
setting
the
ASA
number,
the
aperture
figure
and
the
exposure
correcting
figure
and
by
automatically
determining
the
exposure
time
on
the
basis
of
these
figures
and
the
brightness
of
the
object.
First,
it
will
mechanically
add
the
ASA
number
16