Nikon D100 - Manual (Page 88)

Taking Photographs—Exposur
e
Exposure
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CPU Lenses (All Exposure Modes)
If you are using a CPU lens equipped with an aperture ring, the aperture ring must be
set to the minimum aperture (highest f/-number). At other settings, the shutter release
will be disabled and a blinking
will appear in the aperture displays in the control
panel and viewfinder. Type G lenses are not equipped with an aperture ring.
Depth-of-Field Preview (All Exposure Modes)
To get an idea of how your photograph will look at the
current aperture setting, press and hold the depth-of-
field preview button. The lens will be stopped down to
the aperture value selected by the camera in auto multi
program or shutter-priority auto, or the value chosen by the user in aperture-priority
auto or manual exposure mode, allowing you to preview depth of field in the viewfinder.
3—ISO Auto ( 148)
When ON is selected for Custom Setting 3 (ISO Auto), the camera automatically varies
sensitivity in the range 200–1600 (ISO equivalent) to help ensure optimum exposure
when the limits of the camera exposure metering system are exceeded at the sensitivity
selected by the user. In programmed auto, this helps ensure that the correct exposure
can be achieved with subjects that would otherwise be too bright or too dark. In other
exposure modes, it helps ensure correct exposure at the shutter speed and/or aperture
selected by the user. When sensitivity is altered from the value selected by the user, the
viewfinder exposure-mode indicator (P, S, A, or M) will flash and the sensitivity indica-
tor in the viewfinder (ISO) will be displayed in red. In the camera photo information
display for pictures taken at altered sensitivities, the ISO value will also be displayed in
red. Note that noise is more likely to appear in photographs taken at higher sensitivi-
ties.
ON can not be selected for ISO Auto when sensitivity is set to or ; similarly,
or can not be selected when ISO Auto is on. If a flash is used when ISO
Auto is on, ISO will be fixed at the value selected by the user.
Exposure Mode
Your choice of exposure mode determines how the camera sets shutter speed
and aperture when adjusting exposure. Four modes are available: auto multi
program (P), shutter-priority auto (S), aperture-priority auto (A), and manual
(M).