the last word

I saw this pronouncement on DPR today: The smallest signal we can distinguish from the noise floor is equal to the noise. Signal to noise ratio (SNR) = 1. You see people saying that, or things very much like that, all the time. In some circles, it’s  conventional wisdom.  There’s only one problem: it isn’t even… [Read More]

I’m a big fan of the Arca Swiss C1 Cube. I don’t particularly like their D4 geared head, though. After using the C1 for a while, I find ball heads imprecise and unpleasant to use. However, the C1 can take a while to set up. I tried a combination ball and geared head a few… [Read More]

A week ago I posted some images of Fourier transforms of Siemens Star photographs, and some interesting discussion ensued. Jack Hogan, one of the participants, has written up a guest post showing an interpretation of these plots. I am grateful to Jack for taking the time to do this. Take it away, Jack: A few… [Read More]

This is a continuation of the development of a simple, relatively foolproof, astigmatism, field curvature, and field tilt test for lens screening. The first post is here. Warning: this is a nerdy little post.  don’t know how to interpret it myself. Maybe some of you do. If the words Fourier transform mean little to you,… [Read More]