Cameras and Lenses

This is really interesting. In the first picture what does the blue slider do?

Lately an area of interest of mine in digital photography in particular is scene-referred vs. output-referred image formats and subjective perception. The author (justifiably) walks around this topic in his camera sensor overview, but the data captured by a sensor from photons hitting it doesn’t really contain a readily viewable image.

Data values captured by a modern camera far exceed the ranges that can be reproduced by output media such as paper or screens—meaning that the only way[0] to obtain an image we can communicate to someone else (or future ourselves) as a static artifact[0] is by throwing out data and conforming values to ranges that fit in the output color space, converting scene-referred (“raw”) data to output-referred.

This is where subjective perception comes in: how we perceive colors and shapes in a given scene depends a lot on what we had seen prior to this scene, our general mood, and various other aspects of our mind state. It’s only by taking control of processing scene-referred data that we can use the full range of captured values to try to convey most convincingly, within the constraints of the output space, our subjective perception of the scene around the time we pressed the shutter trigger.

(Naturally, further down this rabbit hole come the questions about e.g. what our conscious perception—but not the camera—was blind to in the scene, and eventually about the nature of reality itself, at which point one may feel compelled to give up and go into painting instead.)

[0] This would be quite niche, but I wonder if we could develop tools for exploring raw data at viewing stage, allowing the audience to effortlessly adjust their perception of the scene (even if within ranges specified by the photographer). Such exploration would require significant computing powers, but we’ll probably be there in a couple of years.

I can only echo my impressed-ness. With or without an interest in the obvious topic, it is well written, well illustrated, accurate. A superb example of the internet at its best.

I built a trinocular microscope mount for my DSLR camera out of a couple of small magnifying lenses. When I was trying to get it to work and improve the quality, I did a bunch of reading on optics. Building your own camera lens that works is pretty easy, but making it capture nice pictures is hard.

Having this article back then would have been a big help! The interactive widgets are great, and it looks like they're entirely home-grown. I am really impressed with the level of detail and work that went into this post.

It changes the focal length of the lens, although it does not seem to affect the lens (blue ring) in the left-hand pane which seems like a bug.

There is a demonstration later in the article (below the 5th mention of "focal length") which does affect the lens (blue ring) in the left-hand pane. Rotate the scene so that you are viewing the camera side-on, and you will see the focal length of the lens changing when you move the slider.