the last word

The Sony a7S switches to high-conversion-gain mode as the ISO dial is moved from 1600 to 2000. Thus ISO 3200 is the first whole f-stop ISO to get the benefit of increased conversion gain. In this post, I’ll show ISO 3200 dark-field images filtered with the same set of kernels as the ISO 100 images… [Read More]

In the previous post, I showed plots of data derived from a series of Sony a7S images of the back of a lens cap at various ISO settings. Now I’d like to show some of the filtered images themselves. Since there are 540 images represented in the plots (10 ISOs, 18 kernel sizes, and 3… [Read More]

Today, I’ll apply the same read noise analysis approach of the last few posts to a new camera, the Sony alpha 7S. The a7S has the — unique in my testing — ability to change its conversion gain as a function if the ISO setting. The conversion gain jumps when the ISO dial is turned… [Read More]

I published some statistics yesterday on D810 dark-field images of various ISOs that had been filtered with low-pass filters of various sizes. I used 1xn kernels to filter out horizontal variations and leave the vertical ones, and nx1 kernels to to filter out vertical variations and leave the horizontal ones. As an adjunct to the… [Read More]

I performed the horizontal and vertical filtering operations of the previous post on D810 dark-field images from ISO 100 to ISO 6400 in whole-stop steps. Here’s the result, for horizontal kernels, which preserve vertical features: And for vertical kernels: You’ll notice that the horizontal kernel results are more nearly straight lines in the log-log graphs,… [Read More]