I found noise in the 5d mk2 at ISO 1200

[Borked Pseudo Mailed]

I tort it was meant to be noise free

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[Colin.D]

Post by Borked Pseudo Mailed
I tort it was meant to be noise free
http://farm4.static.flickr.com/3590/3419636203_83ef7859a7_b.jpg

Any camera will produce noise at almost any ISO speed if the shot is
underexposed, as I suspect that one is. Without the original
unprocessed file to study no further comment can be made.

Colin D.

[Floyd L. Davidson]

Post by Colin.D

Post by Borked Pseudo Mailed
I tort it was meant to be noise free
http://farm4.static.flickr.com/3590/3419636203_83ef7859a7_b.jpg

Any camera will produce noise at almost any ISO speed if the shot is
underexposed, as I suspect that one is. Without the original
unprocessed file to study no further comment can be made.

Let's rephrase that. *Every* camera produces noise.

Reading data from the sensor produces a signal even if
the the lense cap was on and no light at all hit the
sensor. That is a major component of "read noise".

And the sensor output is an analog signal, which is then
digitized, which adds "quantization distortion" (again,
even if there was no light hitting the sensor).

Hence there is always noise with every image made by any
camera. The real question of course is can it be seen,
and in fact proper exposure at low ISO levels will
almost totally mask the noise. As the ISO is increased
the signal level from the sensor, but not the noise
level, is decreased, and it becomes easier to see the
noise.

[Dave Cohen]

Post by Floyd L. Davidson

Post by Colin.D

Post by Borked Pseudo Mailed
I tort it was meant to be noise free
http://farm4.static.flickr.com/3590/3419636203_83ef7859a7_b.jpg

Any camera will produce noise at almost any ISO speed if the shot is
underexposed, as I suspect that one is. Without the original
unprocessed file to study no further comment can be made.

Let's rephrase that. *Every* camera produces noise.
Reading data from the sensor produces a signal even if
the the lense cap was on and no light at all hit the
sensor. That is a major component of "read noise".
And the sensor output is an analog signal, which is then
digitized, which adds "quantization distortion" (again,
even if there was no light hitting the sensor).
Hence there is always noise with every image made by any
camera. The real question of course is can it be seen,
and in fact proper exposure at low ISO levels will
almost totally mask the noise. As the ISO is increased
the signal level from the sensor, but not the noise
level, is decreased, and it becomes easier to see the
noise.

That's all very well and I'm sure you're correct. The thing that bothers
me is I keep reading about noise and get pointed to comparisons on
dpreview (usually huge enlargements of a small portion of the image) and
most of the time I'm not bothered at all by what I see. I'm not saying
it's not there, just that if somebody didn't point it out I wouldn't
have noticed. I guess I'm just not that critical. I know in my film days
I had a lot of grainy pictures and I didn't need any third party
prodding to notice that (and the film was a lot slower than some of
these dslr capabilities).
Dave Cohen

[Floyd L. Davidson]

Post by Dave Cohen

Post by Floyd L. Davidson
The real question of course is can it be seen,
and in fact proper exposure at low ISO levels will
almost totally mask the noise. As the ISO is increased
the signal level from the sensor, but not the noise
level, is decreased, and it becomes easier to see the
noise.

That's all very well and I'm sure you're correct. The thing that bothers
me is I keep reading about noise and get pointed to comparisons on
dpreview (usually huge enlargements of a small portion of the image) and
most of the time I'm not bothered at all by what I see. I'm not saying
it's not there, just that if somebody didn't point it out I wouldn't
have noticed. I guess I'm just not that critical. I know in my film days
I had a lot of grainy pictures and I didn't need any third party
prodding to notice that (and the film was a lot slower than some of
these dslr capabilities).

So we pretty much agree!

Of course one distinction neither of us mentions is that
at exactly what point the noise becomes visibile is
different with each film and each sensor.

So I have an older Nikon DSLR that's just barely useful
at ISO 400, another that is "noiseless" up to ISO 800,
and one that is still reasonable at ISO 4500. I might
not refer to any of them as "noiseless", but shooting at
ISO 4500 and not being blown away by noise is just an
incredibly mind boggling experience for anyone who used
film! :-)