24
C H A P T E R 4
Teach Your Camera New Tricks
To load one of these grids, invoke the entry
Load Grid from File…
. This will
launch the file browser (section 4.10.1). Select the respective grid file using
the
UP
and
DOWN
buttons, and then press
FUNC/SET
to commit or
MENU
to abort. The grid may be switched on or off with
Show Grid Lines
.
4.2.7
Miscellaneous
Values
The
Miscellaneous Values
submenu combines settings for the display of
values related to focus, zoom, and exposure. The first entry,
Show Misc
Values,
determines when these values are shown: not at all (
Don’t
), always
(
Always
), or when the shutter button is half-pressed (
Shoot
). The entry
Show values in video
can be set to show these values while the camera is in
video mode.
Now, let’s have a look at the various information items:
f
The
Zoom Value
can be shown as the zoom factor (
x
), as the true focal
length (
FL
), or as the 35mm equivalent focal length (
EFL
).
f
If you are using a lens converter, such as a telephoto converter or a
wide-angle converter, you can dial its factor into the entry
Adapter Lens
Scale
. For example, if you use a telephoto converter with a factor of
1.75
, dial in the value
175
. This setting will be used to display the focal
length or the zoom factor correctly, and also to compute the depth of
field correctly (section 4.2.8).
The remainder of the display options are exposure-related. The exposure
system of Canon cameras is engineered along the APEX system
(Additive
System for Photographic Exposure)
. This system defines several exposure-
related entities and puts them in relation to each other:
f
Time value ( Tv)
represents the shutter speed.
f
Aperture value ( Av)
represents the lens aperture.
f
Exposure value ( Ev)
represents the joint effect of exposure time and
aperture.
f
Speed value ( Sv)
represents the sensitivity of the sensor (the ISO set-
ting).
f
Brightness value ( Bv)
represents the scene brightness.
Internally, all these values use a logarithmic scale. This makes it easy for the
camera to derive values from each other. The relationship is simple:
Av+Tv = Bv+Sv = Ev
When in auto mode, the camera determines the entities
Av, Tv,
and
Sv
from
the measured scene brightness
(Bv)
. Depending on the program chosen
Figure 4-14
The
Miscellaneous Values
submenu.
This image was compiled from two
display screens.
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