Re: Sony Night SHot Digital VideoCams

["Mark W. Johnson" <markwjohnson@xxxxxxxxxxxxx>]

danzig@xxxxxxxxxxxxxx wrote:
> 
> Hi guys ;')
> 
> I'm asking about the Sony DCR-TRV310V. I was just wondering. In
> general is this camera a good buy ? ...


I had a chance to play with a TRV310 this weekend, and learned alot more
than the marketing literature tells you.  The NightShot mode is more of
a special purpose low light level mode.  But the camera works very well
for IR in the regular modes.

In general, CCDs are sensitive to red, green, blue, and near-IR, but the
manufacturers place color pixel masks over the CCD so that certain
pixels are sensitive to only red, or green, or blue, and in general the
IR sensitivity is masked.  I'm speculating now, but I believe that Sony
probably has some pixels that are red, some green, some blue, and some
with no mask, which give much better low-light performance, as well as
allowing IR through.

The electronics of the TRV310 seem to take everything in and process all
the pixels electronically, and automatically switch between modes.  I
set the camera to normal mode (not NightShot) aimed the camera outdoors,
and got a normal color image.  When I placed a black piece of slide film
(an unexposed picture from the end of the roll, which is an excellent
IR-pass, visible light blocking filter, and is very inexpensive) the
camera automatically switched to a colorless (gray) IR image.  Verrrry
Cool.

Mark W. Johnson

P.S.  I think the only reason people use red filters rather than IR
filters is that humans can see through them.  I suspect that if you
place a red filter over the TRV310, you would probably see a blend of
the red and IR images.  Since the video camera can see perfectly well
through the IR filter, the red filter just partially defeats the IR
effect.
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