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Capital Adventures
October 27th, 2009
09:59 pm
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A physicist duh moment.

A rainbow is produced by total internal reflection of sunlight inside raindrops. Which means that it will be polarised. Which means that with appropriate filtering I should be able improve the contrast somewhat...

The direction of the polarisation will be along the bands, so a polarising filter will only enhance the parts of the arc that are in line with the filter. If the filter is vertical, the sides of the rainbow will be bright and the top will disappear. Twist the filter 90 degrees, and the top will brighten while the sides fade. I only rarely see full arcs anyway, and don't have a wide enough angle lens to capture them if I did, so this isn't a huge limitation. The filter does good things for the foreground clouds too.

So here we have what I think is is my first successful capture of a double rainbow. The secondary is not very bright, but it is there!

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(5 comments | Leave a comment)

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Date:October 27th, 2009 10:32 am (UTC)
That's gorgeous!
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Date:October 27th, 2009 11:53 am (UTC)
Yes, I saw the secondary bow immediately. Nice capture!
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Date:October 27th, 2009 03:35 pm (UTC)
That's good to know about the polarising filter on them! I'll have to try that next time :)
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Date:October 27th, 2009 04:34 pm (UTC)
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Date:October 28th, 2009 04:28 am (UTC)
Very nice. I'm not very good at capturing even single rainbows.
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