BEHIND THE IMAGE | Poison Frog
The strawberry poison frog (Oophaga pumilio, aka -- the blue jeans frog) is high on the list of animals to see and photograph in Costa Rica. Nonetheless, they are tiny, very active, and quite shiny, a combination that makes for a challenging photo subject. I was happy with this picture taken last year in a lowland rainforest. I did shepherd the frog a bit to get him to pose on the little mushroom I wanted but he wandered off looking just fine after the shoot ended.
Here's the thought process I went through while taking this photo.
First, in terms of gear, a macro lens was the obvious choice as these frogs are very small, usually less than one inch long.
Second, this is one of the reasons I love shorter macro lenses instead of the heavy 180 mm macro lenses that many macro photographs seem to favor. These guys move around a lot, so using a tripod would have been very difficult if not impossible. Nonetheless, I find the 50-60 mm macro lenses to be too short for macro work of frogs and butterflies because one must be so close that the animals are easily scared off. I find my 100 mm macro lens to be a good balance between working distance and handholdability.
Third, I needed to consider which camera to use. At the time of this picture, I had a full-frame Canon 5D and 1.6x sensor 40D. The latter body would give me more effective magnification at a given working distance but a small sensor body offers two disadvantages in this situation. First, larger sensors offer less depth-of-field (see here for a fantastic, thorough explanation of this phenomenon). Although this seems counterintuitive for macro photography, I wanted as little depth of field as possible for this image in order to give the image a bit of a dreamy feel and to make the subject really pop. Second, larger sensors offer better high ISO performance. This was in fact the key reason that I chose the 5D over the 40D. Since I knew I would be handholding and working with very little margin for error in terms of focus, I was going to need as much shutter speed as possible.
Fourth, though I'm a big fan of flash, it can be tricky with these highly reflective little poison frogs. Since the light, though low, was quite nice and soft, I decided to work without flash.
Fifth, in terms of the composition, I knew I wanted to frame loosely in order to leave some negative space for the frog to look into and also because I thought the scene would lend itself well for a double-page magazine or book spread. Luckily, the frog cooperated and even gave me a nice pose that set up a triangle in the composition (see below).
Sixth, to meter the scene, my main concern was not blowing out the little cup mushroom, which was quite a bit brighter than the other parts of the image. I was working in aperture priority so I went with my gut feeling and evaluated the scene in its entirety, choosing -1/3 stop of exposure compensation to protect the highlights. Most of the tones in the scene (the greens, the reds, and the browns) were a bit darker than average so without some negative exposure compensation I was afraid the camera would try to bring the tones up to a middle exposure, in the process blowing out the detail in the bright mushroom. A quick check of my histogram after a test shot confirmed that this was a good choice. (Note, I can't remember for sure if I got it exactly right the first time. I may have fiddled with a couple of test shots but it sounds better the way I wrote it above!).
I hope you've enjoyed this post and the thought process behind the image. Successful nature photography is all about previsualizing an image (even when shooting action or capturing a fleeting moment), analyzing the tradeoffs that your previsualized image entails, and then making choices. Hopefully this little article will give you some ideas for the next time that you're out in the field photographing.
If you have questions or comments, please leave them below, and I'll respond as soon as I can.