Looking back, part four

Canada geese Branta canadensis with rainbow in backgroundWe continue our quest to catch up with these images from only nine days ago – yeah, make any comments you like – when a torrential rain came through not long before sunset, followed immediately by a break in the clouds. Knowing what that meant, I trotted outside and, sure enough, there was a prominent rainbow, probably the best I’ve ever seen. It was the classic full-on double rainbow right across the sky, except that it was difficult to get it all in view at once, and I didn’t possess a wide-enough lens to do it justice (though I should have grabbed the film body, which didn’t have the crop factor.) After a few quick shots right out in front of the house, I trotted over to the pond and tried for more fartsy shots there, not having a lot of foreground interest to work with – these Canada geese (Branta canadensis) served when the great blue heron refused to pose and I couldn’t find the cormorant.

There are a couple of traits visible in this frame: the secondary arc is visible to the right within the leaves, and you can see that the colors are reversed between the two. You can also see that the sky is actually a tad darker between the two bows than it is outside of them – this is typical, though not always easy to make out. Rainbow photographs can sometimes be a little tricky, especially if you’re after foreground details, because they almost always occur when the sun is low and this usually reduces the light on the foreground. As such, the sky is much brighter than the ground and the subjects thereon, and a proper exposure depends on how the meter is reading the scene. With the camera aimed largely at the sky, the sky might go a bit dark but the rainbow colors will pop; the foreground, however, is likely to go very dark. Aim at the ground more and the foreground looks better, but the sky may bleach out and even lose the rainbow entirely (I have a few frames like that.) So my advice is to frame a variety of ways, bracket the exposures, and dial in some exposure compensation if you’re familiar with it. Also, using higher contrast and saturation settings will bring out the colors much better, but worsens the difference between the sky and foreground (this image, by the way, was shot at a more saturated setting, but boosted slightly for web display as well.)

rainbow segment with supernumerary arcsAnd now for something curious. When I first went outside, the rainbow was at its most brilliant, and there was a particular effect that was actually visible to the eye, though subtly – it was easy to think it might be imagined, but not only did others see it, I captured it in the images. It can, very faintly, be made out here, but stay with me because I’ll show you an enhanced version in a second. For now, look closely at the underside of the lower arc (the upper one is only faintly visible in this image, but it’s there.) Can you make out a faint band of green and a second band of violet down there immediately adjacent, ‘echoing’ the bow? It’s subtle enough here that it could easily disappear depending on your monitor/screen settings, so let’s take a look at an enhanced version from another frame.

supernumerary rainbow enhanced for contrast
This is a cropped and over-saturated view, but it makes it very clear: there are additional arcs of green and violet under the typical Roy G. Biv lineup (please don’t make me explain that) – in fact, there is even a suggestion of another pair. This is a supernumerary rainbow, and the most interesting thing about it is, we don’t actually know how it occurs [the second most interesting thing about it is, spellcheck didn’t even blink at that word, and it doesn’t even like “zig-zag.”] The only thing I can suggest about the cause of this effect is that the rain really hammered down only minutes earlier and undoubtedly still was at the source of the rainbow, so perhaps the size of the droplets or their proximity had something to do with it.

rainbow reflected in pondAs I said, it was difficult to find a lot of foreground interest to put against the bow. The cormorant that I’ve photographed a few times on these very pilings was nowhere to be seen, annoyingly, but it was gratifying to note that the main bow reflected readily in the water at least; at no point did I see the secondary arc appear in the reflection, but it was high enough that the ability to see it might have required me to be standing in the water itself. I actually tried stalking the resident great blue heron, who wanted nothing to do with any portraits that evening, and couldn’t work out an angle to frame a trio of garden spiders against the reflection. But I’m pretty pleased with the image below, a tight crop from a wider frame. It does make me wonder if it would have been possible to see the rainbow within the raindrops if I’d gone for high magnification macro, but logistically, this might have been near impossible – focus has to be extremely precise in such circumstances and pine needles aren’t the most stable of subjects, bobbing in the slightest breeze. Maybe next time.

raindrops on pine needles against background rainbow

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