Photo: Infected Waxworm

Waxworm
Originally uploaded by C Joe V

Here's the story of this picture. Elissa has been studying Heterorhabditis bacteriophora for about two and a half years now, and by last November had decided she really would like some pictures illustrating its life cycle that she could use in presentations, papers and whatnot. Up to now, she had been using images borrowed from another lab.

When she asked if I could take some pictures for her, I said I didn't think either of the lenses I own would give enough magnification. A decent macro lens would cost almost $500, which was too much to justify for just a couple of little pictures of worms. But there was another option: close-up lenses that screw onto the filter threads of any lens. I indicated that if I were to receive a set of these for Christmas, I would probably be able to take some close-up pictures of her little animals.

I need to clarify something here. H. bacteriophora is a tiny worm -- you need a microscope to see them as anything other than little white specks. What we needed to take pictures of were the moth larvae (wax moths, Galleria mellonella to be specific) that served as hosts for the tiny parasitic worms. The moth larvae are maybe a couple of centimeters long.

Lo and behold, I did get a set of close-up filters for Christmas (guess from whom!), so one day in early January we took almost all the photography equipment I own into her lab to try them out.

First we took some shots of a long-since dead and rather disgusting carcass of a waxworm, in a puddle of clear liquid teeming with the aforementioned little white specks that had killed it. Those were long exposures, since nothing was moving. We killed the fluorescent lights so that the subject would be side-lit by the windows on the other side of the room. Those pictures were pretty gross, but Elissa was happy with them.

The photo above is one of a much healthier waxworm, which had only been infected with the parasites 24 hours before the photo session. Since this one was alive, and crawled around on the posing surface, I had to use flash. Here's the setup: camera, with 50mm f/1.8 lens and some combination of Hoya HMC close-up filters that gave an appropriate magnification, mounted on a tripod with inverted center column looking straight down at the subject; SB-600 flash on-camera, set to TTL with some negative compensation (because the background was black -- but that turned out to be a mistake, as the pictures were all underexposed). I used a fast shutter (1/200, if I remember...) and small aperture (f/8, maybe) so that we could safely turn the room lights back on. The camera was too close to the subject for the flash to light it evenly, so I set up a piece of flexible craft foam (as in A Better Bounce Card) around the non-flash side of the worm and bounced light onto it as best I could with a piece of white paper on the other side of the flash.

I shot in RAW+JPEG mode; the picture you see is the result of processing the RAW file with RAW Therapee and a bit of Photoshop. The JPEG was not usable because I had set the flash exposure too low.

Elissa and I were both fairly pleased with the results.

As a final note, the image you see here is one of the rejects, in case Elissa needs to use the good one in an article in a copyrighted journal. Normally, I follow the Computer Science community in civilly disobeying copyright restrictions on scientific literature when I am the author, but this is not CS and I'm not the author here.