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#1
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High ISO noise
I take a picture with high ISO. Of, course it is a little noisy. My
question is what kind of noise am I seeing? Is it random noise or something else, or a combination of things? Zooming in on a few pixels in a dark area I see individual pixels that are obviously wrong - too bright, incorrect color, etc. If I took the exact same picture again would these same pixels be off in the same way or would different pixels be incorrect this time? Are individual pixels in the camera's sensor non-linear in low-light situations? Is this non-linearity random or is it predicable for a given sensor? - David Harper |
#2
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High ISO noise
David Harper wrote:
I take a picture with high ISO. Of, course it is a little noisy. My question is what kind of noise am I seeing? Is it random noise or something else, or a combination of things? Zooming in on a few pixels in a dark area I see individual pixels that are obviously wrong - too bright, incorrect color, etc. If I took the exact same picture again would these same pixels be off in the same way or would different pixels be incorrect this time? Are individual pixels in the camera's sensor non-linear in low-light situations? Is this non-linearity random or is it predicable for a given sensor? - David Harper Yes. Auntie |
#3
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High ISO noise
David Harper wrote:
I take a picture with high ISO. Of, course it is a little noisy. My question is what kind of noise am I seeing? Is it random noise or something else, or a combination of things? Zooming in on a few pixels in a dark area I see individual pixels that are obviously wrong - too bright, incorrect color, etc. If I took the exact same picture again would these same pixels be off in the same way or would different pixels be incorrect this time? Are individual pixels in the camera's sensor non-linear in low-light situations? Is this non-linearity random or is it predicable for a given sensor? Digital sensor noise is in the 'z' axis, or dynamic (signal level). That is to say that for an image (x,y) each pixel is well and self contained in x,y, and noise due to a high ISO setting is within that pixel. The variance of the noise is higher and higher with a high ISO setting and that is what gives the appearance of noise 'speckles'. (Film on the other hand has larger (x,y) dye 'blobs' with higher ISO as well as the dynamic variance. This is why, generally, one gets much better high ISO results with digital than film). -- -- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. -- usenet posts from gmail.com and googlemail.com are filtered out. |
#4
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High ISO noise
"David Harper" wrote in message
... I take a picture with high ISO. Of, course it is a little noisy. My question is what kind of noise am I seeing? Is it random noise or something else, or a combination of things? Zooming in on a few pixels in a dark area I see individual pixels that are obviously wrong - too bright, incorrect color, etc. If I took the exact same picture again would these same pixels be off in the same way or would different pixels be incorrect this time? Are individual pixels in the camera's sensor non-linear in low-light situations? Is this non-linearity random or is it predicable for a given sensor? - David Harper The bright individual pixels sound like hot pixels. Maybe worth having a read through he http://www.cambridgeincolour.com/tutorials/noise.htm |
#5
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High ISO noise
Mxsmanic wrote:
Alan Browne writes: (Film on the other hand has larger (x,y) dye 'blobs' with higher ISO as well as the dynamic variance. This is why, generally, one gets much better high ISO results with digital than film). My digital results at high ISO are no better than those of film. My ISO 1600 results with a DSLR are much better than those of ~ISO 400 film. David |
#6
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High ISO noise
David J Taylor wrote:
Mxsmanic wrote: Alan Browne writes: (Film on the other hand has larger (x,y) dye 'blobs' with higher ISO as well as the dynamic variance. This is why, generally, one gets much better high ISO results with digital than film). My digital results at high ISO are no better than those of film. Mxmanic is back! (I can't see your OP - Gmail I guess - filtered out). So Mxmanic, please post comparison images to prove the above and specify in clear detail the cameras, lenses, film, sensor settings, etc. I was at a friends house last night and he was showing me some ISO 2500 (Nikon D3) shots printed at about 18 x 14" that showed no grain at a normal* viewing distance and some grain for the pix-peeps. At that, the shot was cropped somewhat. *normal viewing distance being about 1 - 1.5 x the diagonal of the image. -- -- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. -- usenet posts from gmail.com and googlemail.com are filtered out. |
#7
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High ISO noise
Mxsmanic wrote:
David J Taylor writes: My ISO 1600 results with a DSLR are much better than those of ~ISO 400 film. Sure they are. I believe David J -- john mcwilliams |
#8
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High ISO noise
Mxsmanic wrote:
David J Taylor writes: My ISO 1600 results with a DSLR are much better than those of ~ISO 400 film. Sure they are. Yes, they are - here's my example, straight out of the camera: http://www.satsignal.eu/2008-10-04-1432-04.jpg David |
#9
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High ISO noise
John McWilliams wrote:
Mxsmanic wrote: David J Taylor writes: My ISO 1600 results with a DSLR are much better than those of ~ISO 400 film. Sure they are. I believe David J I'm all for Mxmanic posting his evidence... -- -- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. -- usenet posts from gmail.com and googlemail.com are filtered out. |
#10
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High ISO noise
David J Taylor wrote:
Mxsmanic wrote: David J Taylor writes: My ISO 1600 results with a DSLR are much better than those of ~ISO 400 film. Sure they are. Yes, they are - here's my example, straight out of the camera: http://www.satsignal.eu/2008-10-04-1432-04.jpg That has an undersaturated (overexposed) look to me. Did you use a tripod? If so, then why not ISO 100 or 200? Cheers, Alan. -- -- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm -- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm -- [SI] gallery & rulz: http://www.pbase.com/shootin -- e-meil: Remove FreeLunch. -- usenet posts from gmail.com and googlemail.com are filtered out. |
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