Every time I come across one of Bartosz posts, I drop everything to read it. And I learn so much.

The way he builds up the mental model from a simple photon bucket to a pinhole and finally to a lens system is just incredible. I particularly loved the section on the circle of confusion. I've read dozens of explanations on depth of field, but being able to interactively drag the aperture slider and see exactly how the cone of light narrows and the blur reduces makes it click in a way that static text never could. This really should be the standard for digital textbooks.

Amazing as usual.

I am always on the lookout for the classic sin of making it look like electromagnetic waves wiggle in space like a snake. I know it's convenient to glue the tangent space to the underlying physical space, but I think it confuses students.

To be clear: the amplitude of the electric and magnetic fields (and hence their components in each direction) oscillate in space/time. Any particular wave though should travel in a straight line (usual caveats apply). Of course you may incidentally also get e.g. sinusoidal variations in intesity perpendicular to the wavevector, but that will be because of the overall beam characteristics.

I don't mean to say I know a better way to show this, and I am aware of many complicating factors. I just think lots of people (my former students and self included) can come away with a wrong idea about how these waves work.

Can we donate to creative individuals like the OP so they keep making amazing stuff? This is the kind of output LLMs will not be able to produce any time soon.

Doesn't seem to work in Firefox. :(

One past thread (only?) - others?

Cameras and Lenses - https://news.ycombinator.com/item?id=25357315 - Dec 2020 (213 comments)