So this is easy to search on I’ll start a new thread, but this is basically just a continuation of Photographing transparent enamel on silver and Rob’s testing of his lens resolution when stopped down for greater field of focus.
Print the following test target in a size that makes sense to you and photograph it at different f-stops. Compare the results of your various tests to see how your lens handles different aperture settings. You might print in several sizes to test macro close-ups and further-away shots.
https://static.bhphotovideo.com/explora/sites/default/files/bandh-test-target.jpg
It probably makes sense to have this small enough, or far enough away that the very smallest details are not resolved well. If everything looks sharp at every f-stop you aren’t going to learn much.
Fifty or so years ago (scary thought) I used a test target that was a sequence of smaller-to-larger line pairs to test lenses. That target may exist on the web, but this looks as good as any. Photography magazines tested several lenses a month and published the results. Some lenses had best resolution wide open, others nearer to f16. This is why I wonder about the idea that jewelry should be shot at f11. It may well be the case, but there used to be so much variability among lenses that I have my doubts all cameras and lenses do best at f11.
Neil A