[karma mechanic]

Not sure where to post this, but it might be interesting to some of you so here goes.
Yesterday from inside the house there was some late sunshine and rain and I saw a rainbow, which developed into a double rainbow. I leaned out of the window and took two shots, one was on the K-5 with the Tamron 17-50 and the other was on the IR-converted K-7 with the kit 18-55 on it. Two cameras, two different lenses, and in my haste two completely different focal lengths.

I cropped both very heavily, enhanced the tones and saturation, and blew up the IR one to match. Putting them side-by-side you can see the effect of the 830nm filter in the K-7:



In particular looking at the street light at the bottom left you can see how the IR component of the rainbow is inside the red ring in the color version of the outer ring. You can also see how the outer ring has the colors in reverse order compared to the inner ring.

There's another oddity. In this IR-only shot with a great deal of contrast enhancement you can see bands of brightness inside the main IR ring (the top ring):



The 830nm filter is completely black to the naked eye, so what color is causing those concentric rings at shorter wavelengths than IR?

[BassPeer]

I guess the prism effect of the particles in the air splits light not only into visible light but also into uv- and ir-light. These wave-like rings in your third photo might be interferences or simple overlaying lighwaves, but I don't actually think that one can see light intereferences by eye or an usual camera. I suppose first-, second-, third- and-so-on-order light might be cues as well.

[dhauser]

Hi. These images are fantastic. Would you mind if I used them in a book on the electromagnetic spectrum? Thanks.

[grunter49]

Hi, the one on the right looking at it is the rainbow ,the other is it`s reflection in the drizzle.

[jbinpg]

This is a real double rainbow which is caused by double reflections inside the rain drop itself. The supernumary rainbows seen in the original posters images are also explained here:

Rainbow - Wikipedia, the free encyclopedia

Jack

[karma mechanic]

Since I posted that first one I managed to get another series of shots of a rainbow, but this time it was with a bit more care and using the same prime lens both times.
The difference in timing between the shots was as long as it took to switch the lens from one body to the other, so a few seconds.

First the colour one, on the K5 with the DA15:


Secondly, the modified K7 with the DA15, and like before it shows extra rings inside the 'normal' rainbow:


And finally an image with sections from both shots (aligned with the fixed features of the roof and tree), showing how the IR part of the rainbow is displaced:


Even in colour there is a hint of the extra rings inside, I'm guessing that there is some UV involved here and the modified camera isn't filtering it.

dhauser - I have no objection to you using the images, I can provide the originals. Please PM me.