Miscellaneous Values - Canon Camera Hackers Manual

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C H A P T E R 4
Figure 4-14
The Miscellaneous Values submenu.
This image was compiled from two
display screens.
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
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:
The Zoom Value can be shown as the zoom factor (x), as the true focal
f
length (FL), or as the 35mm equivalent focal length (EFL).
If you are using a lens converter, such as a telephoto converter or a
f
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:
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
f
aperture.
Speed value ( Sv) represents the sensitivity of the sensor (the ISO set-
f
ting).
Brightness value ( Bv) represents the scene brightness.
f
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
buttons, and then press FUNC/SET to commit or MENU