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, it’s probably a good idea to move on.
In this post, I showed the center, edge and corner renderings of a Siemens Star captured with a Sony 12-24 mm f/4 lens on a Sony a7RII. A couple of people wondered what the Fourier transform of the images that I posted there would look like. With the aid of Brandon Dube, I wrote this Matlab code:
I exported the files from Lightroom, passed them through the above code, and this is what resulted for the lens set at 24 mm:
And at 18 mm:
At 12 mm: