Canon CHDK - Manual (Page 11)

Override shutter speed [0 – 100] <Extra Photo Operations < Main Menu
TV in the OVERRIDES display in the OSD. This feature allows you to override the camera’s
shutter speed in all auto and manual modes with the speed you select. This feature allows shutter
speeds as long as 64 seconds, (or longer if your camera has CHDK Extra Long Exposure
support) and as short as 1/100,000
th of a second, in 1/3 rd EV steps. This setting is affected by
the “Value factor” and the “Shutter speed enum type” settings below. Please note that the actual
speeds available are dependent on the camera used and other conditions such as the aperture
setting.
•
Value factor [Off, 1/100k – 100] or [Off , 1,10,100]
Enables the Override shutter speed and sets the Value factor, the use of which is described
below.
• Shutterspeed enum type [Ev Step , Factor]
Select the method of determining the override shutter speed.
Ev Step – The method most of us will use. Enables the first set of options above.
The Override shutter speed is shown in seconds. Select the desired shutter speed and
set the Value factor to 1 to enable the override function.
Factor – This method will enable the second set of options above.
The shutter speed is determined by multiplying the selected value factor with the
selected shutter speed. This method is useful in analytical and research photography.
ND filter state [ Off / In / Out] (For cameras with an ND Filter)
When the camera detects a really bright scene, it will swing the ND filter inline with the lens and
sensor. This makes the scene look darker and will affect the exposure (but not depth of field like
a real aperture / iris would). With the ND filter in, the camera can select a slower shutter speed
without over-exposing the entire scene. Also, with the ND filter swung in, the camera will
capture an image with an aperture of f/8 - This is an artificial aperture value caused by the ND
filter swung in. With CHDK, you can choose to keep the ND filter out, and just select a faster
shutter speed to compensate. To do this, Select one of the options from -
▪ 'Off' means the camera will automatically control the ND filter state.
▪ 'In' means the ND filter is swung in.
▪ ' Out' means the ND filter is kept out.
Override Aperture [Off , 2.77 – 16.00] <Extra Photo Operations < Main Menu
For cameras with an actual aperture/iris. mechanism (IXUS / SD models have ND filter).
AV in the OSD. This feature allows you to override the camera’s aperture settings. Simply
select the desired aperture setting and the camera will use that setting in all auto and manual
modes. Please note that the actual aperture values available depend on the camera.
Override Subj. Dist. Valu [0 – 65535]
SD in the OVERRIDES display in the OSD. This feature allows you to specify, to the millimeter,
the manual focus distance. To focus the camera at the override distance you must half-press the
shutter.
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