This spider web really has rainbows thanks to a complex and slightly weird combination of physics and biology. Not just iridescence, but an ever-changing rainbow that shifts all over the web in the morning hours. It’s one of those shots that when I was looking through the camera I figured no one would believe it hadn’t been photoshopped (it wasn’t, I even have video!). While there is a lot of cool science going on here involving light and the unique properties of spider webs to create the effect, it’s also one of the prettiest things I have seen through my viewfinder. And that is coming from years of capturing nature photos all over the planet!
Coffee and Rainbows
A few months ago, as I was making my regular morning journey from office to coffee pot, I glanced out our patio door and caught a glimpse of a rainbow in the upper corner of our screen enclosure. “That’s pretty…need coffee”, I thought, as I stayed on course to my caffeination station.
For me, seeing a random rainbow is nothing new. I have dealt with migraines for most of my life, accompanied by visual auras. I see rainbows and sparkles all the time around light sources right before a migraine hits, it’s a pretty tradeoff for feeling like your skull is trying to strangle your brain. After filling my coffee, I wandered back, and saw it again. Still, not believing my eyes, I tilted my head back and forth, took off my glasses, squinted, squatted up and down, and generally looked like a crazy person. Despite all my contortions, it was still there, so I grabbed the camera, aka my “reality meter”. Looking at the live view will usually tell me if it’s just the migraine messing with me or a genuine natural phenomenon. To my pleasant surprise, it was still there on the screen. Thus began the next two weeks of our photo shoot with “Rai”, the Rainbow Spider*.
Tips and Techniques
The Set Up
I used a step-ladder, a tripod, and a variety of lenses, including a Tamron 180mm macro, 70-200mm, and 150-600mm. I have always made a habit of using extended height tripods, there have been many situations like this where the added height is a distinct advantage. My wife also used a similar setup, most often using her Tamron 18-270mm lens.
The rainbow phenomenon only appeared for about two hours each morning. As the sun rose and the light angle changed, the rainbows would appear or disappear at different distances and angles. At first, when the colors started to fade at one spot, we would move and hunt for the next best place. After the first two days, I was able to mark the best spots on the ground with tape, noting the ideal time at each for the brightest colors and the time when they would fade. This made future set up easy as we were able to leave the ladders and tripods in place for the next day.
Working the web, this was the “macro” position. For these up close shots, this ladder had a hole in the top step that was perfectly sized to slip my monopod through, setting its foot on the ladder’s tray. This provided an extremely stable base, critical to producing sharp macro images.
Compose Your Background First
Rai’s web was perfectly positioned to have a terrible background, she couldn’t have done a better job! With wildlife (and really any photography) I believe you should always compose your background first. It is very easy to get caught up in the moment, and miss little things in the background that detract from your overall image. A good background should complement your subject, not compete with it for the viewer’s attention.
Little shifts in your position can pull distracting elements out of the frame, and bring in more pleasing colors or textures. In this case, I had the bonus of being able to create my background. I built a stand out of scrap PVC pipe, and draped a black tablecloth over it at a short distance behind the web. This served to provide a clean, dramatic background, that really emphasized the colors and structure of the web.
My wife, Nicole, is not just the Hahn Nature Photography business manager, but also an excellent photographer, too! One of the cool things for us was being able shoot the same subject and compare our photos. We each came away with very different images, and inspired each other to try different compositions.
Change It Up
In nature photography we are often making decisions on the fly to capture fleeting moments. However, since Rai wasn’t going anywhere, we had a chance to learn from each image and brainstorm together for different creative ideas. We constantly changed things up, trying different settings, angles, heights, lenses, and equipment. When possible, I do much the same in the field, first grabbing my four “standard” shots (distant record shot, animal in its environment, closer horizontal for the two page spread, and a tight vertical for the cover!), and then getting more creative if the animal chooses to let me into their world for a while longer.
These were some of the different compositions we tried. Some I think worked well, some like my abstract high-key concept…not so much.
In a situation like this where there was consistent light and background, going manual for exposure produced the best results. With a black background, the camera left to do its own metering on one of the auto modes will tend to wash out and overexpose this scene. By taking control and manually selecting all the settings, I choose to underexpose by about a stop, keeping the background dark and really livening up the colors.
Science Sidebar: Sticky Droplets -or- What the @#$%! Is Going on Here?
I am endlessly curious and addicted to learning, so I had to know why the rainbow appeared. After much searching online for answers, I contacted a variety of scientists to unravel and understand why this occurred. While there were a number of hypotheses, the general consensus and short answer is “sticky droplets”.
The rainbows that appear on the web are thanks to many factors; high humidity, the angle and position of the sun relative to the web, the diameter of each strand, proximity of each strand to other, and on, and on. According to one of the physicists I contacted, this combination and interaction of factors is so complex it probably could never be properly modeled and reproduced. It’s simply too many variables.
First, light passes both through and around the translucent spider silk. The light passing through is refracted, like light going through a prism to make a rainbow. The light going around is diffracted, like the rainbow patterns on the back of a CD. Rai’s web was at just the right height off the ground for us to see these effects. Second, the reason spider webs are sticky is that when spiders make them they also deposit very small sticky droplets of a glue-like aggregate silk at regular intervals along the web. The more regularly spaced and the closer together these droplets are, the more likely they will produce this rainbow effect. Think of how a rainbow forms by light passing through tiny droplets of water in the air. Apparently spider goo can have a similar effect on light, and I guess Rai was very good at evenly and closely spacing her micro droplets.
“Rai” is an orchard spider (Leucauge venusta), a member of the orb weaver family. Also known as an Orchard Orbweaver, or Venusta Orchard Spider, this is a small, brightly colored spider, found throughout the Americas from Canada to Colombia. As a point of reference for her size, she would completely fit inside a quarter with her legs extended, and her body is smaller than most people’s pinky nail. The genus name Leucauge is derived from the Greek word leukos, meaning both “white” and “bright, clear, brilliant”, and it is actually the only spider name created by Charles Darwin himself. Venusta is Latin for charming, elegant, or beautiful (see http://www.spiders.us/species/leucauge-venusta/). So Rai is a “Brilliantly Beautiful” spider!