I do wonder if sensor site size affects dynamic range. On August 6, 2014 8:05:44 AM PDT, Bryan Jacoby <bryan.jac...@gmail.com> wrote: >I don't claim to know if the K-3 is or is not more noisy than the K-5. >I'm just talking about the fundamental question of noise in more vs. >fewer pixels. Read noise, etc., is a whole other ball of wax, but >photon statistics is the one thing that you can't get away from with >ever-improving technology. Throw different in-camera jpeg engines >into the mix and really this is a comparison not worth making, if you >want a basic understanding of how pixel count relates to noise. > >I remember in the original glowing DXO reviews of the K-5 they >mentioned that some noise reduction is applied even to RAW files at >high ISO. > >On Wed, Aug 6, 2014 at 10:45 AM, Zos Xavius <zosxav...@gmail.com> >wrote: >> That's not factoring in read noise, processing and quite a few other >> variables. My take is that the K-5 series produces cleaner files out >> of the box at any ISO. How much I can push shadows without seeing >> noise is of great interest to me. I feel that you can likely get >files >> from the K-3 with equal noise characteristics with post processing, >> but honestly, side by side jpegs out of the camera reduced to web >> resolution show more noise from the k-3. Also you have to factor in >> the resolution loss when the k-5 hits over 1600. Its clearly doing >> some NR wizardry in its pipeline and reducing the resolution >somewhat. >> How much the K-3 does that I do not know, but have read that it does >> something similar. >> >> On Wed, Aug 6, 2014 at 10:07 AM, Bryan Jacoby ><bryan.jac...@gmail.com> wrote: >>> It's all about photon counting statistics a.k.a. Poisson statistics >>> a.k.a. shot noise: http://en.wikipedia.org/wiki/Shot_noise >>> >>> If we ignore the mysteriuos details of de-Bayering (let's pretend >all >>> cameras are like the Leica M Monochrom), and that we are in a >>> situation where photon counting statistics are the dominant source >of >>> noise (which is what we should be talking about, since we are >>> concerned with the fundamental question of noise in more vs. fewer >>> pixels, not other noise sources that will vary from one sensor >design >>> to another), then all that matters is how many photons end up each >>> pixel of the final output image. >>> >>> Consider this simple case: you want to order an 8 x 12 print from >>> Mpix, which they will print at 250 dpi, for a final output image >with >>> 6 MP, and we don't do any noise reduction. >>> >>> If you take the image with a 6 MP sensor (kind of like a K100D >>> Monochrom, but with a modern sensor), each sensor pixel/photosite >will >>> translate directly to an output pixel, so input or sensor image >noise >>> = final image noise. >>> >>> If you take it with a 24 MP sensor (K-3 Monochrom), each photosite >>> will on average get 1/4 as many photons as the K100D's photosites. >>> Poisson statistics tell us that the noise goes as the square root of >>> the number of photons, so each of these pixels will have a >>> signal-to-noise ratio (SNR) that's only half of the SNR of the K-3 >>> pixels. But when you average together groups of 4 pixels from the >>> K-3, the SNR of the aggregated pixels will increase by the square >root >>> of 4, which is 2. 1/2 * 2 = 1; like I said it all comes out in the >>> wash. >>> >>> On Tue, Aug 5, 2014 at 5:38 PM, steve harley <p...@paper-ape.com> >wrote: >>>> on 2014-08-05 13:50 Bryan Jacoby wrote >>>>> >>>>> I think this idea of bigger/fewer pixels leading directly, as in >>>>> through the very basic physics of photon noise, to lower noise is >>>>> wrong-headed.I couldn't care less what the signal-to-noise ratio >of >>>> >>>>> _pixels in my sensor_ is. What I care about is the SNR of pixels >in >>>>> the output image, whether that be an image displayed on a screen >or >>>>> the dots made by a printer. >>>> >>>> >>>> i have pondered this too, and i suppose the question is whether one >could >>>> average the pixels on a 24 Mp sensor to get as clean a 12 Mp image >as from a >>>> 12 Mp sensor; i suspect there are multiple factors beyond the >number of >>>> photons hitting a photosite that make the relationship non-linear >(so that >>>> lower Mp would net lower noise even after averaging) >>>> >>>> but since in general we'd expect the 24 Mp sensor, in bright enough >light, >>>> to capture much more detail with a comfortably low noise floor, i >think we >>>> have to choose between low-ISO detail and high-ISO SNR >>>> >>>> >>>> >>>> -- >>>> PDML Pentax-Discuss Mail List >>>> PDML@pdml.net >>>> http://pdml.net/mailman/listinfo/pdml_pdml.net >>>> to UNSUBSCRIBE from the PDML, please visit the link directly above >and >>>> follow the directions. >>> >>> -- >>> PDML Pentax-Discuss Mail List >>> PDML@pdml.net >>> http://pdml.net/mailman/listinfo/pdml_pdml.net >>> to UNSUBSCRIBE from the PDML, please visit the link directly above >and follow the directions. >> >> -- >> PDML Pentax-Discuss Mail List >> PDML@pdml.net >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> to UNSUBSCRIBE from the PDML, please visit the link directly above >and follow the directions.
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