Nikon D3100 - Manual (Page 148)

132
i
Adjust ISO sensitivity ( 0 71).
❚❚Auto ISO Sensitivity
If Off is chosen for Auto ISO sensitivity in P, S, A, and M modes,
ISO sensitivity will remain fixed at the value selected by the user
(
0 71). When On is chosen, ISO sensitivity will automatically be
adjusted if optimal exposure can not be achieved at the value
selected by the user (ISO sensitivity is adjusted appropriately
when the flash is used). The maximum value for auto ISO
sensitivity can be selected using the Max. sensitivity option in the Auto ISO
sensitivity menu (choose lower values to prevent noise (randomly-spaced bright
pixels, fog, or lines); the minimum value for auto ISO sensitivity is automatically set to
ISO 100). In modes P and A, sensitivity will only be adjusted if underexposure would
result at the shutter speed selected for Min. shutter spd (
1 /
2000
–1 s; in modes S and M,
sensitivity will be adjusted for optimal exposure at the shutter speed selected by the
user). Slower shutter speeds will be used only if optimum exposure can not be
achieved at the ISO sensitivity value selected for Max. sensitivity. If the ISO
sensitivity selected by the user is higher than the value selected for Max. sensitivity,
the value selected for Max. sensitivity will be used instead.
When On is selected, the viewfinder shows ISO-AUTO and the
information display ISO-A. These indictors blink when sensitivity
is altered from the value selected by the user.
ISO Sensitivity Settings G button
➜ C shooting menu
A
Auto ISO Sensitivity Control
Noise (randomly-spaced bright pixels, fog, or lines) is more likely at higher sensitivities. Use
the Noise reduction option in the shooting menu to reduce noise (
0 134). Note that ISO
sensitivity may be raised automatically when auto ISO sensitivity control is used in
combination with slow sync flash modes (available with the built-in flash and SB-900,
SB-800, SB-600, and SB-400 flash units), possibly preventing the camera from selecting slow
shutter speeds.