Nikon D300 User Manual page 199

Long Exp. NR
(User's Manual: D300S page 258; D300 page 262)
Long exp. NR
to combat visual noise in long exposures. Noise is that ugly,
grainy look the image has when it's underexposed and then
brightened or when a really high
used. If you ever shoot film, you'll remember how faster
films have lots more grain. Well, noise is like that, except
uglier. It's the digital equivalent of static in music. Who
wants static in their images?
Nikon knows its imaging sensors well, and feels that images
taken at exposures longer than 8 seconds may exhibit more
noise than is acceptable for normal use. The imaging sensor
can start to warm up a little when longer exposures are used.
This causes a condition called amp noise, in which warmer
sections of the imaging sensor start to display more noise than
other sections.
There are two settings for Long Exposure Noise Reduction
(Long exp. NR), as shown in
▪ On: When you select On, and the exposure goes over 8
seconds, the camera will take two exposures with the
exact same time for each. The first exposure is the
normal picture-taking exposure. The second is a black
frame subtraction exposure, in which an image is made
for the same length of time as the first one, but with the
shutter closed. The noise in the black frame image is
examined and then subtracted from the original image.
It's really quite effective and beats having to blur the
(Long Exposure Noise Reduction) is designed
Figure
199
ISO sensitivity
3-43.
setting is