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Monday, November 14, 2016

Waterton Lens Flare

The green, blue and red hexagons in the trees weren't created by Photoshop; I shot this photograph on film on Mom and Dad's T70 back in 2002. Maybe I shouldn't be surprised, but I think it's neat how cleanly the light bouncing around in the lens split perfectly into red, green and blue...although now I wonder why there aren't also a yellow, indigo, violet and orange flares as well. Hmmm, well, that's the wonder of science! I'm sure someone smarter than me will explain in the comments. The Earliad depends on its readers for exactly this purpose! 


Jeff Shyluk said...

Look at the strange colours of the lens flares, and you'll see that they aren't the product of normal refraction. You'd expect to see primary colours, like from a glass prism.

I believe I've finally figured it out: your parents' T70 has (I am guessing) a "purple" coated lens. Lens coating has no colour, typically it's a thin layer of magnesium fluoride, which as a refractive index close to that of glass. Lens coating is applied to prevent the glass from generating its own reflections, which is lens flare. Since the glass has both transparency, thickness, and an optical curve, each lens has two surfaces that can create reflections. If the light reflections are of two different wavelengths, or if the wavelengths are in different phases because they pass through differential thicknesses in the glass, then your lens will reflect refracted colours. The colours will be whatever isn't absorbed by material, or in the case of the lens, what escapes the camera through refraction.

Your lens flares are green, cyan, and orange, since that is what is being refracted through your camera absorbing green on the CCD sensor, thanks to the interaction between your lenses and the magnesium fluoride. Put another way, you on the outside of the lens see purple (or at least not-green), while the camera sees and records green (not-purple). If your lens has a coating that appears green the refracted colours would be on the reverse side of the spectrum - purple, pink, and yellow.

See this picture from a pukey puke-ridden Apple 5, from the Apple line of products which make me puke:

Apple uses on their cheap lenses cheap coating which appears green and makes aggressively purple flares.

Earl J. Woods said...

I like that explanation, though there's no CCD sensor involved in this case; it was shot on film...