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#21
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Nikon D3S (12.1 Mpix, FF, very high ISO, HD video)
"Paul Furman" wrote in message ... Alan Browne wrote: Paul Furman wrote: DRS wrote: Why do Nikons seem to have a base ISO of 200? Is it a trade off of some kind? It allows a higher max ISO. No relevance really. Is it just coincidence that low-ISO sensors on P&S start at lower ISOs? I don't understand the details but the general principal seems to apply. It could be that the P&S small-pixel sensors are relatively less efficient in light capture (the non-sensitive electronics occupies a larger fraction of the pixel area), and hence need more light to fill the well. This being an additional problem to their small size, and hence fewer photos, and hence greater shot-noise. David |
#22
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Nikon D3S (12.1 Mpix, FF, very high ISO, HD video)
"D. Peter Maus" wrote in message
... On 10/14/09 16:37 , Savageduck wrote: On 2009-10-14 14:07:08 -0700, "D. Peter Maus" said: On 10/14/09 15:53 , Savageduck wrote: On 2009-10-14 11:04:56 -0700, "D. Peter Maus" said: On 10/14/09 12:56 , Savageduck wrote: On 2009-10-14 10:45:43 -0700, Alan Browne said: Read all the gory details of this new body: http://www.dpreview.com/news/0910/09101402nikonD3s.asp Interesting. It seems to me the real benefit is going to be in high ISO performance and the addition of sensor cleaning. I am not drawn to the video in DSLR trend. Not being a pro or independantly wealthy I guess I am going to stick with my D300 for now. That D300 is no slouch, either. I'm happy with it, and I still have my D70 lifeboat. LOL! Yeah, I still shoot my D70 daily. If you like D300 see if you can get your hands on a D700 for a weekend. The D700 thing is something I have been thinking of for a while now. You'll never need another woman. Well I have been on my own for almost two years now, and even though I have the social life of a stump, a little feminine companionship wouldn't be too bad from time to time. There is nothing more disturbing than a 60 year old in hormonal distress. :-) I'm right behind you at 58. At 72 I'm ahead of both. Lots of fun years left, hopefully for all of us. Differences: Although I have a D300, with my 200 as a backup, I am seriously thinking of a D5000 because the articulated LCD should give my back more mileage. -- Peter |
#23
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Nikon D3S (12.1 Mpix, FF, very high ISO, HD video)
"John Sheehy" wrote in message
... "DRS" wrote in . au: Why do Nikons seem to have a base ISO of 200? Is it a trade off of some kind? The D3 uses a low silicon fill factor, and makes up for it with large microlenses, which, of course, fill the wells faster. In order to meter at ISO 100, the camera would have very little RAW highlight headroom, so ISOs under 200 are only offered as special modes. Apparently, they use the low fill factor to get more noiseless electronics at the photosites. This keeps read noise down a bit, but increases shot noise a little, too. Would you please explain this concept in English? I know about SNR and why I get more noise at a higher ISO, but I don't understand the difference between read noise and shot noise. -- Peter |
#24
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Nikon D3S (12.1 Mpix, FF, very high ISO, HD video)
"Peter" wrote:
"John Sheehy" wrote in message ... "DRS" wrote in . au: Why do Nikons seem to have a base ISO of 200? Is it a trade off of some kind? The D3 uses a low silicon fill factor, and makes up for it with large microlenses, which, of course, fill the wells faster. In order to meter at ISO 100, the camera would have very little RAW highlight headroom, so ISOs under 200 are only offered as special modes. Apparently, they use the low fill factor to get more noiseless electronics at the photosites. This keeps read noise down a bit, but increases shot noise a little, too. Would you please explain this concept in English? I know about SNR and why I get more noise at a higher ISO, but I don't understand the difference between read noise and shot noise. "Photon shot noise", or "photon noise", or "Poisson noise" or "shot noise" are all references to the fact that light doesn't hit the sensor at a constant steady rate. The rate variation results in noise because the actual exposure is for some specified interval. Two adjacent pixel locations may be illuminated exactly the same, but in the particular interval that light was allowed to fall on them it is very likely that one pixel will get more light (light for that pixel was arriving at a faster rate than for the other). The difference between the signal from those two pixels is shot noise. Shot noise looks like a paper covered with a mix of salt and pepper! It is also greater for more exposure (the variation in rate increases as the amount of light increases). Hence the place it is usually seen in images is in the sky, or clouds, or other featureless highlights. (So maybe we should say it looks like a paper covered with a mixture of white salt and light grey pepper.) Above a certain amount of exposure, the SNR of an image is very likely to be determined by photon noise, in which case it is called "photon noise limited". Read noise is all noise that is in the image as a result of reading the data from the sensor (even if the lens cap is on and absolutely no light has hit the sensor and therefore the signal is 0). The base level of analog voltage fluctuation on the sensor adds to it. Things such as clock frequency variations in the ADC add to it. In most discussions quantization distortion is included in the "read noise". Read noise has, like shot noise, a Gaussian distribution so it is essentially random, and will mostly be seen in the shadows. To continue the analogy used above, it looks very much like a paper covered with mixture of black pepper and grey pepper. Below a certain amount of exposure, the SNR of an image is very likely to be determined by read noise instead of shot noise. (Generally that is not a good thing.) Because read noise will be seen in the shadows it is generally more annoying to the human eye. -- Floyd L. Davidson http://www.apaflo.com/floyd_davidson Ukpeagvik (Barrow, Alaska) |
#25
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Nikon D3S (12.1 Mpix, FF, very high ISO, HD video)
"Floyd L. Davidson" wrote in message
... "Peter" wrote: "John Sheehy" wrote in message ... "DRS" wrote in . au: Why do Nikons seem to have a base ISO of 200? Is it a trade off of some kind? The D3 uses a low silicon fill factor, and makes up for it with large microlenses, which, of course, fill the wells faster. In order to meter at ISO 100, the camera would have very little RAW highlight headroom, so ISOs under 200 are only offered as special modes. Apparently, they use the low fill factor to get more noiseless electronics at the photosites. This keeps read noise down a bit, but increases shot noise a little, too. Would you please explain this concept in English? I know about SNR and why I get more noise at a higher ISO, but I don't understand the difference between read noise and shot noise. "Photon shot noise", or "photon noise", or "Poisson noise" or "shot noise" are all references to the fact that light doesn't hit the sensor at a constant steady rate. The rate variation results in noise because the actual exposure is for some specified interval. Two adjacent pixel locations may be illuminated exactly the same, but in the particular interval that light was allowed to fall on them it is very likely that one pixel will get more light (light for that pixel was arriving at a faster rate than for the other). The difference between the signal from those two pixels is shot noise. Shot noise looks like a paper covered with a mix of salt and pepper! It is also greater for more exposure (the variation in rate increases as the amount of light increases). Hence the place it is usually seen in images is in the sky, or clouds, or other featureless highlights. (So maybe we should say it looks like a paper covered with a mixture of white salt and light grey pepper.) Above a certain amount of exposure, the SNR of an image is very likely to be determined by photon noise, in which case it is called "photon noise limited". Read noise is all noise that is in the image as a result of reading the data from the sensor (even if the lens cap is on and absolutely no light has hit the sensor and therefore the signal is 0). The base level of analog voltage fluctuation on the sensor adds to it. Things such as clock frequency variations in the ADC add to it. In most discussions quantization distortion is included in the "read noise". Read noise has, like shot noise, a Gaussian distribution so it is essentially random, and will mostly be seen in the shadows. To continue the analogy used above, it looks very much like a paper covered with mixture of black pepper and grey pepper. Below a certain amount of exposure, the SNR of an image is very likely to be determined by read noise instead of shot noise. (Generally that is not a good thing.) Because read noise will be seen in the shadows it is generally more annoying to the human eye. Thanks for that explanation. My interest as a photo artist is simply to make a nice picture. When Nikon says I can shoot at a higher ISO with less noise, I am skeptical. I have a friend who claims he shoot a D300 at ISO 1,600 without little perceptible noise. Yet I have not found that to be the case on my D300. -- Peter |
#26
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Nikon D3S (12.1 Mpix, FF, very high ISO, HD video)
"Peter" wrote in message ... [] Would you please explain this concept in English? I know about SNR and why I get more noise at a higher ISO, but I don't understand the difference between read noise and shot noise. See: http://www.clarkvision.com/imagedeta...mance.summary/ and related pages. David |
#27
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Nikon D3S (12.1 Mpix, FF, very high ISO, HD video)
"Peter" wrote in message ... [] Thanks for that explanation. My interest as a photo artist is simply to make a nice picture. When Nikon says I can shoot at a higher ISO with less noise, I am skeptical. I have a friend who claims he shoot a D300 at ISO 1,600 without little perceptible noise. Yet I have not found that to be the case on my D300. If you look closely enough, you will see noise even in ISO 100 images. My Nikon D5000 has an ISO 3200 setting which produces better results than my compact camera does at ISO 400. Is it noise-free? No. Is it usable for the circumstances where I have to use ISO 3200? Most certainly. If you want to "make a nice picture", ensure you have enough light that you can shoot at ISO 100 with a small camera, ISO 200-400-800 with your DSLR, according to what /you/ judge to be noise-free results, at the image size you will finally be viewing. Cheers, David |
#28
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Nikon D3S (12.1 Mpix, FF, very high ISO, HD video)
On Fri, 16 Oct 2009 16:09:45 GMT, "David J Taylor"
wrote: "Peter" wrote in message ... [] Would you please explain this concept in English? I know about SNR and why I get more noise at a higher ISO, but I don't understand the difference between read noise and shot noise. See: http://www.spamlinksnipped.com/image...mance.summary/ and related pages. David Except that that is nothing but blatant misinformation. He posts those findings to slant them toward his own cameras, trying to justify his own purchases. He never takes into account any newer technology that destroys the results of all his old biases. Then idiots like you regurgitate those pages to perpetuate his nonsense because you know no better. |
#29
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Nikon D3S (12.1 Mpix, FF, very high ISO, HD video)
Paul Furman wrote:
Alan Browne wrote: Paul Furman wrote: DRS wrote: Why do Nikons seem to have a base ISO of 200? Is it a trade off of some kind? It allows a higher max ISO. No relevance really. Is it just coincidence that low-ISO sensors on P&S start at lower ISOs? I don't understand the details but the general principal seems to apply. The lowest ISO should have no bearing on the max ISO. With most sensors, gain (higher ISO numbers) is simply analog gain (pre-conversion) for the first few stops (from say 100 - 800 or 1600) and afterwards it is is digital gain. (Although recent higher ISO cameras from Canon and Nikon may have more analog gain before relying on digital). So there is no limit imposed by the lowest sensitivity. |
#30
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Nikon D3S (12.1 Mpix, FF, very high ISO, HD video)
D300 can produce very acceptable photos even at ISO 3200 when and if the
light is almost daylight as color temp (over 4000 K) with a even smooth spectrum. For ex the interior of a house illuminated from windows, when the reflective surfaces are mostly neutral. No matter how low is this light. As long as the light is of "full spectrum" even very dim, the picture will have not suffer to much from noise. A second parameter is the dynamic range of the light in the photo. If the darkest area in the photo is not darker than 5-7 EV, then this is a factor to not develop the noise in an inconvenient way. So, even luminance and good spectrum are the factors that can produce pictures with less ugly noise. The remaining noise is more even luminance noise (less or no ugly chrominance), more like a powder, as film grain, that sometimes can add to beautiful bokeh, if exists. From the other hand a bad light source, as the green or orange mercury street lights with the terrible spectrum, or the dim tungsten lights with yellow or brown lampshade that produce light of very low temp, often less than 2000K can push the cameras WB adjustment out of the limits even at ISO 200. For ex if the light has a temp of 1800K (not rare), the blue channel is almost absent. In that case if we (or the camera) try to correct the color, not 100%, but even a little just to look more natural and full, we will amplify the blue channel even by more than 5 EV,. That means that even if we shot at 200 ISO, the blue channel will be amplified to even higher than ISO 6400 and then the noise will be terrible. So under circumstances, we can have almost perfect photos at ISO 3200 and under other very noisy under ISO 800 (or less). Bad light quality and wide luminance range of the subject are the enemies of the low noise photo -- Dimitris M ....I have a friend who claims he shoot a D300 at ISO 1,600 without little perceptible noise. Yet I have not found that to be the case on my D300. |
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