On 17/09/06, graywolf <[EMAIL PROTECTED]> wrote: > Can you provide a reference on that? A quick goggle search* finds > nothing the contradicts my explanation. Your comment may be accurate on > the quantum level but I do not think we can quite apply it to current > image sensors, but would be interested in seeing something about where > you are getting that from. Photons, like all quantum particles, are very > slippery critters and probably act that way, but I do not know of any > photo diode that gives out a quantized signal --in a macro world sense. > I admit my physics knowledge is not as up to date as it could be. But > I do believe folks are trying to digitalize non-digital phenomena, if > the information was digital we would not need an ADC.
It's still an analogue signal it's just not continuous, an ADC is still required in order to produce digital representations of the voltage levels. You have to consider that real size of the photo diode component of the sensor. Its width is only tens of wavelengths (considering active sensitivity to about 700nm) across (6.05 x 6.05um) in the case of the sensor in the K10D and it may only be two or three atoms deep, this is why numbers like 40k electrons for saturation are being bandied about (though I suspect that the sensor in the K10D would be closer to about 32k, unfortunately Sony specs aren't direct comparable with those from the majority of other manufacturers). It's a bit mind contorting but the analogue output of the sensor is governed by the electron count so if the devices were noiseless you would see discrete steps in the analogue output. -- Rob Studdert HURSTVILLE AUSTRALIA Tel +61-2-9554-4110 UTC(GMT) +10 Hours [EMAIL PROTECTED] http://home.swiftdsl.com.au/~distudio//publications/ Pentax user since 1986, PDMLer since 1998 -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
