Thread: Why do digital cameras need shutters?
View Single Post
  #13  
Old February 23rd 06, 05:48 AM posted to rec.photo.digital.slr-systems
Lionel
external usenet poster
  
Posts: n/a
Default Why do digital cameras need shutters?
On Thu, 23 Feb 2006 02:28:06 GMT, opined:

For "noise reduction mode" for long exposures; yes. For normal
purposes, cameras may use blind pixel borders on the sensor. The 20D,
for example, has a vertical strip of 74 pixels wide on the left side of
the image, and a horizontal strip 12 tall on the top. The data from
these is where the JPEG engine and RAW converters get their black values
from (and they serve a s a noise sample as well). They are actually
contained in the RAW .cr2 file, and black is left with the offsets still
in them and in the exposed image (average is typically 128.2 to 128.4).

That's fascinating information, John, thanks for passing it on.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------