I have developed a test for “ISOlessness” as part of the photon transfer analysis program. The test is described here. Here’s a summary: You specify the highest ISO that you wish to consider, and what the mean signal level should be at that ISO as a ratio to full scale. For example, if you’re interested… [Read More]

Yesterday, I reported on modeling the a7II at each ISO. Earlier, I modeled the camera over the same ISO range. The difference is that the first method yields a series of read noise numbers, one for each raw channel at each ISO, while the second method produces two read noise numbers for each channel, which… [Read More]

In the post before last, I modeled the Sony a7II over a range of in-camera ISO settings, and reported on the results. Today, I’ll show you what happens when you model the camera one ISO at a time. This is a much simpler task, aside from the fact that you have to do it over… [Read More]

Yesterday, I presented the result of fitting the a7II data to the standard photon-transfer model. Today I’ll compare those results to two other cameras, the Nikon D4 and D810. Here are the numbers: In the table above, we separate the read noise into two components, as described earlier. The first is the read noise on the… [Read More]

Now that I’ve taught DCRAW and my Matlab analysis program to be on the same page with the a7II files, I set about to find the read noise (RN) and the full well capacity (FWC) of the camera across a range of ISOs. I told the modeling program to consider all ISOs from 100 to… [Read More]