Archive | July 2012

How to shoot against a black background

European preying mantis (Mantis religiosa) [Canon 7D, Canon 100mm macro, three speedlights Canon 580EX]

I must admit that I have never liked photos taken at night that showed the subject, be it an insect or a person, against a pitch black background. If I am ever in a situation when a full-flash photo at night is the only option, I always try to put some light on the background by either framing the shot in such a way that something lighter is behind my subject (e.g., a large leaf behind an insect), or use an extra light, a second flash or a headlamp, to illuminate the background. I do not buy the argument that black background is the “natural” background for night organisms: there is nothing natural about an artificial, narrow beam of light illuminating a single subject; I cannot think of any animal, other than a person with a flashlight, who sees the world in this way. But there are situations where the black background can produce an esthetically pleasing, striking effect. Lightly colored or semi-translucent organisms look great against a black background, and black is also a good choice to show the highlighted outline of a creature.

Emasculating bot fly (Cuterebra emasculator) photographed on a piece of glass against a black background [Canon 7D, Canon 100mm macro, three speedlights Canon 580EX]

Shooting against a black background in a studio setting is a bit trickier than shooting against a white background. Any misdirected light will bounce off the dark background, and make it less than perfectly black, and imperfections of the dark background are likely to be more visible than imperfections of the white one.

It is also important that the object you are shooting is not resting directly on the black background. I use black velvet, which reflects relatively little light, but if a small insect sits directly on top of it then the fabric’s texture will be plainly visible. Thus, I place any subjects that can be shot in a vertical position (a plant, an insect on a branch) at least 20-30 cm away from the background, usually by holding it in a “helping hand” clamp. If the animal needs to sit horizontally, or if I want to shoot it from above I place it on a piece of glass or clear plastic, held horizontally about 20 cm above the black velvet. In the latter case it is very important that the lights are positioned in such a way that reflections on the glass are minimized (unless a visible reflection is something that you want); proper positioning of the lights can only be found by trial and error, and the glass should be as clean as possible because any smudges or specks of dirt will show against the background.

Here is the setup I use for my black background photography.

My basement photo studio

A. Black velvet – it is important that the velvet is draped uniformly, without folds or wrinkles; they will reflect light and show as lighter patches in your photo.

B. A piece of thin glass or clear plastic – I use it to move the subject away from the background; if the background is too close its texture will show in the photo.

C. Two diffused side lights – I use Canon 580EX/580EXII flashes in Photoflex LiteDome XS Softboxes; these softboxes are very light, and can be easily folded and stuffed into a camera bag for use in the field.

D. Backlight – another Canon 580EXII, placed high above the black stage, diffused with a large sheet of white paper; I often turn this light off and only use the two side lights.

Multi-flowered spikelets of Northern sea oats (Chasmanthium latifolium) [Canon 7D, Canon 100mm macro, three speedlights Canon 580EX]

When a bumblebee is not a bumblebee

Emasculating bot fly (Cuterebra emasculator) [Canon 7D, Canon 100mm macro, three speedlights Canon 580EXII]

Yesterday afternoon my wife called me and pointed out a large insect crawling on the lawn. “Look,” she said, “this is the largest bumblebee I have ever seen.” The insect indeed looked like a big bumblebee as it slowly buzzed, trying to take off. But when I looked closely I immediately realized that it was not a bumblebee, but a fly.

It was not the first time I encountered this particular kind of fly, a member of the family Oesteridae, or a bot fly. These flies are quite pretty as adults, big and fuzzy, similar in their appearance to carpenter bees or bumblebees. They have no functional mouthparts, which means that they cannot bite anybody or feed on anything, and as adults live only for a few days. But earlier in their life they were rather nasty creatures.

The first time I experienced an intimate encounter with a bot fly was a few years ago in Costa Rica, when after a few weeks in the country I found two fat maggots of these parasitic insects embedded deep in my left arm. How they got there makes for quite an interesting story: following the mating a female bot fly had caught a live mosquito, and deposited an egg on its body; a tiny larva hatched almost immediately and waited for the mosquito to land on the host, (me, in this case); once there, the larva disembarked the mosquito, and buried itself into my skin. I only started feeling that something was living in me when the larvae were about two weeks old, and well entrenched in my tissue. This species of bot fly (Dermatobia hominis) attacks people and other primates, but other than it being unpleasant to have a maggot digging in your tissue, usually don’t cause too much damage to their host. This is because we are a very large host for a relatively small parasite.

A bot fly larva extracted from Max’s skin [Canon 7D, Canon 100mm macro, three speedlights Canon 580EXII]

But in NE North America bot flies attack much smaller hosts – squirrels, mice, and other rodents – and can cause substantial injuries. Often they leave their host severely disfigured, and the wounds they create can cause massive infections. The species we found yesterday, ominously named Cuterebra emasculator, was even implicated in causing sterility of male squirrels by selectively attacking their testicles; luckily for squirrels this turned out not to be the case. Unlike the Neotropical human botfly, North American species do not employ mosquitos to propagate their larvae, but lay eggs near rodent burrows, on rocks or directly on the surface of the soil. The eggs then stick to the fur of the intended hosts, and their body heat stimulates the larvae to hatch.

Dogs often fall unintended victims to bot flies, and last fall our always inquisitive Max contracted one while digging for chipmunks. Thankfully, we found and removed it early on in its development, when the larva was still small and easy to extract. Occasionally, people also get infected with North American bot flies.

Max

Red-headed Bush Cricket

A Red-headed Bush Cricket nymph cleaning its antenna [Canon 7D, Canon MP-E 65mm, speedlights Canon 580EXII]

Even a simple dog walk can turn into a voyage of discovery. Last weekend, when letting my dogs chase chipmunks in Estabrook Woods, I found this little gem of a cricket, a species I had never seen before.
It was a nymph of a Red-headed Bush Cricket (Phyllopalpus pulchellus), also known as the Handsome Trig (on the account of being both handsome and a member of the subfamily Trigonidiinae.) This species can be easily identified by the large, paddle-like mandibular palps, which these insects move in a fashion very similar to the way jumping spiders move their palps, and I wonder if their function might be spider mimicry.
The adults of this species are still a few weeks away, and they are even prettier than this immature individual, with black body and a crimson red head. I definitely will be on the lookout for them in August.

Update: I found an adult Red-headed Bush Cricket exactly one month later; read about it here.

A closeup of the head of a Red-headed Bush Cricket nymph showing enlarged palps [Canon 7D, Canon MP-E 65mm, speedlights Canon 580EXII]

Don’t talk too loudly, somebody may be listening

Next time you see some wild flowers growing on the side of a road, look closely, and if you are lucky you may be able to spot an ambush bug. These small, cryptic insects are members of the genus Phymata, who in their feeding habits and some of the elements of their morphology resemble miniature praying mantids. Although related to stink bugs and other members of the order Heteroptera, ambush bugs are sit-and-wait predators of insects, and like praying mantids carry large raptorial front legs, capable of catching prey twice the size of their own bodies.

An adult ambush bug female [Canon 7D, Canon MP-E 65mm, Canon 580EXII speedlight]

This in itself is pretty cool, but ambush bugs are capable of something that no other insect in the world can do: they can have a conversation with you. Well, maybe not a real conversation, but they can hear you, and they will reply to the sounds humans make.

A young nymph of the ambush bug (Phymata americana) from Concord, MA [Canon 1Ds MarkII, Canon MP-E 65mm, Canon MT-24EX twin light]

Both immatures and adults of ambush bugs are capable of producing sounds by using a stridulatory mechanism on their thorax. But unlike other stridulating insects, such as grasshoppers or katydids, the principal role of the sounds they produce appears to be not attraction of a mate, but rather fooling their prey into coming closer. Many insects, more than we have ever suspected, use acoustic signals to communicate, and ambush bugs exploit this behavior.

In order for the signal to be effective in attracting other insect, ambush bugs need to be able to mimic the sound of their intended prey. And thus they have evolved the ability to mimic many sounds they can hear. Prof. Matija Gogala from the Slovenian Museum of Natural History has made an incredible recording of an ambush bug having a “conversation” with a person whistling to the bug, and you can listen to it here.

Alas, the sound these insects make is too quiet for most of us to hear, and you would need a specialized microphone to pick up their replies. But still, I think it is pretty amazing that there is a tiny creature hiding somewhere in the bushes, listening to me and repeating my words, hoping that maybe I will get close enough that he can have a shot at catching me for dinner.

The amazing flying gooseberries

Male flying gooseberry (Bullacris sp.) from Richtersveld, South Africa [Canon 1Ds MkII, Canon 180mm macro, two speedlights Canon 580EX]

If you ever find yourself in South Africa during southern spring, and stay up long into the night, until midnight at least, you may be rewarded with one of the most incredible acoustic displays that the insect world has to offer. For this is the time when the bladder grasshoppers, known in Africa as the flying gooseberries, begin to sing.

These insects are rather strange. They are grasshoppers, placed in their own family Pneumoridae, but it would be difficult to tell by looking at one. To begin, they are huge – some species are the size of a small mouse. Their legs are thin and spindly, and they cannot really jump. But what they lack in athletic abilities is amply compensated by their ability to make noise.

Flying gooseberries produce sound in a way similar to other grasshoppers, by rubbing their hind legs against a row of pegs on their abdomen (to be exact, most grasshoppers rub their legs against a modified vein on their wings, but the principle is the same.) This in itself wouldn’t be unusual, if not for their ability to amplify the sound. The male’s abdomen – because it is he who produces most of the sounds – has evolved to become an enormous, balloon-like structure, filled with air and acting as a powerful resonator. This allows him to broadcast his song at distances that have no parallels among insects – a single male can be heard from over a mile away. (Click here to hear a flying gooseberry’s song.) The males can also fly, and are sometimes attracted to camp fires at night, which is the reason for their vernacular name (and if they get too close to the flames they promptly explode.)

The female is nowhere near as extrovert, and she only responds to the male’s call with short, quiet clicks, which the male can hear from over 50 m despite the racket he himself is producing. By being much quieter she also avoids the risk of being detected by predators and parasitoids, some of which use the insect’s calls to locate their prey. But in every population some males of flying gooseberries take advantage of the fact that the singing rival gathers all the attention. Rather than singing themselves they stay quiet, and sneakily intercept the females attracted by the caller. They even assume the appearance of females by not developing wings or the enormous abdomen. This prevents them from being chased away by the singing male, who confuses them with the real deal. This to me proves it once again that insects were the first to invent pretty much every behavior imaginable, including the transvestites.

Female flying gooseberry (Bullacris sp.) from Richtersveld, South Africa [Canon 1D MkII, Sigma 15mm EX DG Diagonal Fisheye, Canon MT-24EX twin light]

My rainforest portrait studio

Leaf katydid (Typophyllum sp.) from Suriname [Canon 1Ds MkII, Canon 180mm macro, two speedlights Canon 580EX + ambient light; f11, 1/4 s, ISO 250]

Katydids of the tribe Pterochrozini are some of the best leaf mimics that you can find in the Neotropical rainforest. Or rather the best mimics that you cannot find, as their resemblance to leaves, both green and shriveled, is so exquisite that in my 18 years of working in the Neotropics I have never found one during the day. I only find them at night, when their movement betrays their animal nature, or when I am able to detect their ultrasonic calls with a high frequency microphone.

Upon finding one I usually take a photo, but I never liked those pictures, illuminated only with a flash, the background pitch black. I much prefer images that show the true colors of the background of the animal, and I like to have full control over the quality of light, its direction and intensity. Since I nearly always catch the katydids (they are my professional speciality, and I need the specimens for my work), this gives me an opportunity to photograph them again the following day, using the full photographic arsenal and methods at my disposal.

Leaf katydid (Typophyllum sp.) from Suriname [Canon 1Ds MkII, Canon 180mm macro, two speedlights Canon 580EX + ambient light; f6.3, 1/40 s, ISO 200]

One of the first things I do when setting up a camp in the rainforest is to build a small workbench. On it I process the specimens, enter field data into my computer, and I use it as a photographic studio. Every species I collect is photographed for documentation, and the photos are entered into a database. These photos are not particularly pretty: they are mostly close-ups of diagnostic characters of the animals, and  composition or any other esthetic considerations are completely irrelevant.

But once I am done with the work, the fun begins. Because I usually keep my insects alive for a few days in order to get recordings of their songs, I can then experiment with all variables of their portraiture, such as the depth of field, backlighting, magnification etc. For this type of photography I nearly always use long lenses, which both give me a great working distance, and help diffuse the background and bring out the main subject of the photograph.

Here is a typical setup I use for my rainforest portraiture. I built this little field studio while working in southern Suriname in 2010, and the two photos of Typophyllum katydids shown here were taken in it. The bench itself was made from leftover pieces of wood that was used to construct our research camp.

My field studio in Suriname

A. Canon 1Ds Mk II – this is my main full frame workhorse; I like to use full frame cameras when shooting with really long portrait lenses (180mm); a camera with a cropped sensor  would force me to  move too far back from the table, and it would also make it more difficult to achieve a shallow depth of field.

B. Canon EF 180mm f/3.5L Macro – a wonderful macro lens; it is very sharp, but its bokeh could be better (bright points in the background tend to appear as octagons.)

C. Canon ST-E2 Speedlite Transmitter – it allows me to trigger multiple external flashes wirelessly.

D. Tripod GT2531EX 6X Carbon Fiber Explorer – in order to get natural-looking, light background, the exposure time must be relatively long, often as much as several seconds. This means that the camera must be firmly immobilized, and hand-holding it is not an option. I love this tripod – it is light but sturdy, and it allows me to spread the legs flat on the ground, giving me a very low vantage point.

E. Canon Remote Controller TC-80N3 – The use of a remote controller allows me to eliminate vibrations caused by manually pressing the shutter.

F. Canon 580EX speedlight – a powerful, pretty water-resistant flash (but not waterproof!)

G. Diffusers – this cheap piece of plastic (a $1 plastic folder I bought at Staples) is one the most important parts of my equipment. Without it the light of the flash is far too concentrated, resulting in harsh, unpleasant burnouts on any highly reflective elements of the photo.

H. GorillaPod – a great little tripod; very flexible, you can wrap it around a branch, and some models are sturdy enough to support a large SLR with a heavy lens.

I. “Helping hands” – another indispensable piece of gear for anybody interested in macrophotography; it allows you to position a leaf or a branch, or support a piece of paper if you want to have white background for your photo. Get it for a few bucks at RadioShack.

J. Reflector – I always carry one; it allows me to put nice, reflected light on the subject, especially if I am using only ambient light and no flash.

K. Wimberly Plamp – a handy flexible arm to hold the reflector or a branch.

Stay away from my cucumbers

My wife has been trying to grow cucumbers for years. Her thumbs are as green as the fuzzy layer of mold on my tent after a month in the Ghanaian rainforest, and yet the fickle plant had refused to produce any reproductive structures for years. Until now.

Yesterday she harvested her first, beautiful cucumber from her lone, fragile plant. It was beautiful. It was tasty. With a thin slice of smoked salmon and Kristin’s own proprietary sauce it made the most delicious snack I had had in years.

But I was not the only one lusting after the elusive fruit. Striped cucumber beetles (Acalymma vittatum) apparently love them as much as I do, and Kristin’s plant was already overrun with these insects. I promptly obliged her request and collected them off the plant, with the implied understanding to take care of them in some kind of a permanent fashion.

Striped cucumber beetle (Acalymma vittatum) on a cucumber tendril [Canon 7D, Canon MP-E 65mm macro, three speedlights Canon 580EXII]

Cucumber beetles are fascinating creatures. Their sense of smell is second to none, and they can find cucumber plants using both the volatiles produced by the flowers, which have evolved to attract pollinators, and those produced by leaves, which have evolved to repel herbivores. In fact, cucumber beetles manage to incorporate in their bodies some of the compounds that the plant is producing for the very purpose of making itself unpalatable, and even advertise this fact with their gaudy coloration.

How could I possibly hurt something this interesting and pretty? After I had taken this photo I let the beetles wander off, but before they left I had sternly warned them never to come back, or we would need to talk.