Nikon D5100 Guide D’Exploitation

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Adjust ISO sensitivity (
0 54).
❚❚Auto ISO sensitivity control
If Off is chosen for Auto ISO sensitivity control in PSA, and M 
modes, ISO sensitivity will remain fixed at the value selected by 
the user (
0 54).  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 Maximum sensitivity option 
in the Auto ISO sensitivity control 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 Minimum 
shutter speed
 (
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 Maximum sensitivity. If the ISO sensitivity selected by the user is higher 
than the value selected for Maximum sensitivity, the value selected for Maximum 
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 High ISO NR option in the shooting menu to reduce noise (
0 154).  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 optional 
SB-900, SB-800, SB-700, SB-600, and SB-400 flash units, possibly preventing the camera from 
selecting slow shutter speeds.