On Sun, 16 Mar 2003 02:25:06 -0500, "Sanman" <me@you.com> wrote:

>"George" <gpapaioa@ford.com> wrote in message

>news:d49be77c.0303132100.25a7aaf3@posting.google.com...

>> "Sanman" <me@you.com> wrote in message

>news:<v6tuevhf3fb0da@corp.supernews.com>...

>> > "George" <gpapaioa@ford.com> wrote in message

>> > news:d49be77c.0303112033.60a3fa50@posting.google.com...

>> > > Considering that I am looking for an extra back-up camera that is good

>> > > in lo-light situations, I may look no further than the JVC DV3000u. I

>> > > like the fact that it has a larger 1/3.6" CCD and 540 lines rez and

>> > > bad either. I hear it is

>> > > better that the TRV950 in lo-light. Any opinions/experences out

>> > > there? It is surely one of the best looking miniDV camera's ever.

>> > >

>> > > I am not too excited about the low cost 3CCD options out there with

>> > > tiny CCD (1/6", 1/4.7", etc.) that demand lotsa light.

>I dissagree... totally.

Yes...;-)

>> > I was always under the impression that larger CCDs needed more light

>because

>> > the image is spread out over a larger area, and therefore is darker.

>Some

>> > of this has to do with the size of the lens. If it is large, it can

>gather

>> > more light and when that light is focused down to a very small area, it

>> > should be very bright indeed. What laws of physics have changed in the

>last

>> > 10 years? I would be more worried about the precision of a small chip

>than

>> > it's light gathering ability. If the LENS is big enough, you should get

>> > excellent low light quality when the light is concentrated on such a

>small

>> > point. Does the architecture of those small chips play a role in light

>> > gathering? I mean, each pixel is smaller, but the light is stronger

>because

>> > it's condensed on to a smaller area, so that should make up for it. No?

>> >

>> > Sanman

>> Well you were under the wrong impression!!!

>> There are compromises involved with the lens, but the bigger the CCD -

>> the better it is in lo-light.

>Why on earth would a smaller CCD with the same number of pixels need more

>light?

>

>If you have two cameras with the same diameter, and the same number of

>pixels on their CCDs, except that the first CCD is 1/4" and the second is

>1/2", the camera with the 1/4" CCD will have better low light capabilities.

>Because both cameras have the same lens diameter, they are both gathering

>the same amount of light. In the first camera, the chip is smaller so the

>lens is set up to focus it's gathered light on a 1/4 inch area. In the

>second camera, the same amount of light has to be spread out over a wider

>area (1/2") and therefore the amount of light that reaches each pixel is

>less. It's like the same amount of butter on a larger piece of bread. You

>just get less butter per bite. If the larger CCD has more pixels, well

>that's a different story. In pro cameras, the large CCDs produce less noise

>because they have more pixels. They also require a larger lens to gather

>more light for the larger CCDs. If you have a larger piece of bread, you

>need more butter.

>

>Please explain why you think this is not so.

>

>Sanman

If you assume that each pixel (in same-pixel-count CCDs)

is illuminated the same (with a given subject light level

and lens stop used), and that the pixel characteristics

are identical except for size (the larger requiring a

larger CCD area to accommodate them, and a larger lens

to cover the same angle of view [but this second is

irrelevant since the light levels and *relative*

apertures have been specified as the same...]), and if

it is obvious that all else is equal and that the

greater-area pixels will receive more light due solely

to their greater receptor areas, then the larger CCD

*will* be more sensitive than the smaller... (And, I

think your lens "conceptions" are off a bit...;-)