Fred Miranda wrote: highdesertmesa wrote:
Found this on the P2P site. It sounds like the way they calculate DR seems to be a compromised choice to use Full Well Capacity over White Level as the latter requires too much data. So perhaps some of the DR of the M10/M10-P we see in their DR chart at ISO 100 is being overestimated.
In any case, as you've shown in your examples, ISO 200 should be the base ISO for the M10-P, and at ISO 200, the M10-P shows on P2P to have a PDR of 10.2 while the M10-R at ISO 100 shows a PDR of 10.7.
Given the above, the M10-P only equals the M10-R for DR (according to P2P chart) if you're ok with throwing away almost all the DR in the highlights by using ISO 100. And if the P2P chart is wrong, as I suspect it is, then you may actually be getting lower DR on the M10-P at ISO 100 than you do at ISO 200.
Although the sensor is not linear beyond the White Level, with proper calibration; corrected values can be determined.
In fact, a properly calibrated sophisticated decoder can recover highlight values beyond the ADC clipping point.
Given this fact, it is unclear whether White Level or Full Well Capacity should be used as the upper bound in Dynamic Range calculations.
As a practical matter, because determining White Level requires a great deal of data, I use Full Well Capacity in my Dynamic Range calculations.
Could you run a similar test on your Leica M10-R?
Shoot under high contrast lighting over-exposing the scene by 1EV (use exposure compensation for example). Set the shutter dial to "A" and do not change aperture between shots. So only change ISO from ISO 100 to ISO 200. In post, just normalize the files (usually by reducing exposure back to normal) and compare the highlight areas at 1:1.
Sure, I'll give it a try. There may be some non-equal footing, though, due to the fact that the M10-R meter may be less likely to overexpose in the first place. Did you use Live View or the optical finder when getting the exposure? If you used Live View, which metering method do you have it set for? Just want to make sure I mimic what you did as closely as possible.
May 31, 2021 at 09:18 PM
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