Nikon D300 User Manual (en)

The Memory Buffer
The camera is equipped with a memory buffer for temporary storage, 
allowing shooting to continue while photographs are being saved to the 
memory card.
Up to 100 photographs can be taken in succession; note, 
however, that frame rate will drop when the buffer is full. In rare cases, 
frame rate may also drop when a microdrive memory card is used.
While photographs are being recorded to the memory card, the access 
lamp next to the memory card slot will light.
Depending on the number 
of the images in the buffer, recording may take from a few seconds to a 
few minutes.
Do not remove the memory card or remove or disconnect the 
power source until the access lamp has gone out.
If the camera is switched 
off while data remain in the buffer, the power will not turn off until all 
images in the buffer have been recorded.
If the battery is exhausted while 
images remain in the buffer, the shutter release will be disabled and the 
images transferred to the memory card.
See Also
For information on choosing the maximum number of photographs that 
can be taken in a single burst, see Custom Setting d5 ([Max.
release], pg. 282).
For information on the number of pictures that can be 
taken in a single burst, see page 405.