Sunday, November 1, 2015

How Does Light Travel Through Glass?

This will be a bit of a diversion post. Photographer's these days are concerned with many technical things... how many megapixels their cameras are, how much dynamic range they can fit in an image, how many stops of aperture they can manage. On a deeper and more edifying level, there is a lot of science behind how modern cameras work, but perhaps the most elemental is the fact that glass is transparent. "It just is" you may say, but the physics of why some things like camera lenses let light through, and why other things don't, is explained in this link to Brady Haran's excellent Sixty Symbols channel on YouTube. Professor Phil Moriarty explains:



But camera lenses don't just pass light through unimpeded.If if the photons do make it through the glass, they will travel through the glass 40% slower than they would in a vacuum. This is where the concept of diffraction comes in, the basis of how camera lenses work....

First of two videos with Professor Merrifield:




Second video, again with Professor Moriarty:


1 comment:

  1. Hi there, this article is very interesting.

    I wrote an attempt to explain how this could possibly make modern lenses less transparent (therefore less saturated with lack of perspective drawing, etc) in order to be nicely corrected and sharp for modern sensors. I, of course, based myself on the ramblings on another individual on youtube and a lot of things have changed in my head since I wrote the article but please have a read.

    yannickkhong.com/blog/2015/10/4/the-flattening-of-modern-lenses-or-the-death-of-3d-pop

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