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New Information on K3III

Started May 5, 2021 | Discussions thread
JeremieB Senior Member • Posts: 2,041
Re: New Information on K3III

Lotz wrote:

I asked the question to Bill, how he comes to that perfect DR curve, and he explained everything about the slope (which is absolutely clear) and that shot noise DR is poisson distributed resulting in a SNR of Sum(e)/Sqrt(Sum(e)) = SQRT(Sum(e)).

So the totplolgy of the curve is well explained and quite clear. ( i am also developping cameras for driver montioring and traffic sign recognition systems in automtive).

But I have no clue about the offset of the curve, why DR is limited to 11.57EV @ ISO 100. Is this based on a total electron flux? For me , that induces that there is an upper limit of FWC depending on sensor size, as with no read noise, DR translates to SQRT(FWC).

I think this page from Bill's site is what you're looking after:

https://www.photonstophotos.net/GeneralTopics/Sensors_&_Raw/Sensor_Analysis_Primer/Engineering_and_Photographic_Dynamic_Range.htm

By the way, an equivalent full frame lens has ~2,25times the entrance pupil of an APSC-lens, thus 2,25x higher light flux. But this is projected on a 2,25x higher area, so the luminance denisty is the same. Per pixel you are integratin 2,25x the light assuming the same resolution, so that's why the DR of FF is ld(2,25) above that of APS-C. Everything clear, but the explanation of the absolute values is somehow missing. Unfortunately, the thread did not allow furhter posts, otherwise I had asked bill for that.

BR

Markus

 JeremieB's gear list:JeremieB's gear list
Pentax K-70 Pentax K-3 Mark III Pentax smc FA 50mm F1.4 Pentax smc DA 18-55mm F3.5-5.6 AL Pentax smc D-FA 100mm F2.8 Macro WR +9 more
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