spiderweb

This phenomena caught me totally off guard. One morning, I noticed colored irisations coming from a spider web with the low morning sun illuminating it. Taking a closer look with my camera, I noticed that if I defocused the web slightly, the colors became larger and interesting. After that, I got the macro lens out and really took a close up look at the colors, and what I saw was astounding -- very distinct and vivid colored diffraction bands. Turns out that others have noticed these bands, and according to Les Cowley, the phenomena defies a clear understanding.

This is the first out-of-focus photo I took which hinted at the interesting colors in some parts of this spider web.

Here are the wonderful color bands (or spectra) that are visible from the slightly out of focus spider web and DSLR with a macro lens.

Here is a copy of a photo from a book by Dawkins (sent by Les Cowley) showing the periodic structure of a web fiber as well as an enlargement showing the complicated internal fibers that provide strength and elasticity for the web. Apparently, these structures provide the geometry to produce the diffraction bands seen above.

More spider web diffraction pics here and extensive information here.