Re: Nikon D40 vs D40x ISO newbie question

C J Campbell wrote:
On 2007-04-28 20:12:18 -0700, "Private" <please@xxxxxxxxxxx> said:


"Roger N. Clark (change username to rnclark)" <username@xxxxxxxxx> wrote in
message news:4632E33E.9070200@xxxxxxxxxxxx
Private wrote:
From KR review of D40x
http://www.kenrockwell.com/nikon/d40x.htm
ISO 100 - 3,200. Per the laws of physics, a 10MP sensor has to run at
lower ISOs for the same performance as a 6MP sensor of the same physical
size. Therefore the D40x' ISO range starts at ISO 100, not ISO 200 as the
D40. The "wider range of ISOs" touted as a feature is actually a
downgrade: the D40 didn't need to go slower than ISO 200 for great
results, and at ISO 100 the D40x is more likely to have more blur or
shallower depth of field.
Please excuse my ignorance, and explain this law of physics.

"a 10MP sensor has to run at lower ISOs for the same performance as a 6MP
sensor of the same physical size. "

and do you agree with KR's statement above?

TIA


There is no actual change in sensitivity in terms of quantum
efficiency, but smaller pixels collect fewer photons.

See:
http://www.clarkvision.com/imagedetail/does.pixel.size.matter

http://www.clarkvision.com/imagedetail/digital.sensor.performance.summary


Roger

Thanks for these informative links, they helped me to understand John
Sheehy's answer.

Actually, there is something seriously wrong with Roger's analysis. It simply does not accurately predict results. According to his theory, the Canon 1D Mark III will produce worse pictures than a Nikon D100. This is demonstrably untrue.

I have no problem with scientific analysis. I just expect that it should have reproducible results.

No, you are incorrect. See my other post.
The 1D Mark III is not on the charts.
Canon states the photo sites collect the same number of photons as
the 1D Mark II (closer pixel pitch but better micro lenses), so
the 1D Mark III should plot at 7.4 microns on a line horizontal
to the 1D Mark II. That puts it still performing better
than a 350D or a D70.

Roger
.

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