If On is selected, photographs taken at shutter speeds slower than 1 s will be processed
to reduce noise (bright spots, randomly-spaced bright pixels, or fog). The time required
for processing roughly doubles; during processing, “job nr” will flash in the shutter
speed/aperture displays and pictures can not be taken (if the camera is turned off
before processing is complete, the picture will be saved but noise reduction will
not be performed).
In continuous release mode, frame rates will slow and
while photographs are being processed, the capacity of the memory buffer will drop.
Long exposure noise reduction is not available during movie recording.