Photographing Gelatinous Zooplankton
Jellies present a wealth of photographic opportunities, both in their natural environment or when held captive in an aquarium. Since many are transparent or nearly so, lighting for the image can be a challenge. When done properly, photos of gelatinous animals can be among the most stunning and beautiful of any of the seas creatures.
Using captive jellies is a surprisingly effective way to create beautiful photos. With controlled conditions you can reduce some of the problems that cannot be easily eliminated in the field, such as particles that cause backscatter. The key factor, particularly for highly transparent specimens, is to provide lighting from the top or side. Standard front lighting will only pass directly through the animal and not reflect sufficient light back to the camera and film to form a distinct image. For this reason you will need access to the top or side of the aquarium for placement of the flash unit. This makes it difficult to photograph jellies in a public aquarium if using a flash as the primary source of light.
The photographic chamber should ideally be placed in a darkened room to minimize the chances of reflections from other light sources. You can reduce the problem of reflections even more by wearing dark clothes and gloves. A small light can be placed over the aquarium to provide aid for focusing and composition control. The glass or acrylic surface through which you will be photographing should be absolutely clean. Bubbles and other debris on the inside surface should be wiped some time before the photo session to allow particles a chance to settle out. Suspended particles will reflect light to the camera and show up on your photograph as conspicuous white spots. If the water is excessively cool, you may experience problems with condensation on the outside of the aquarium that must be continuously wiped away with a sponge or squeegee. It is best to use water that is only as cool as necessary to help minimize this problem. Double pane glass or thick acrylic will also reduce condensation. As a background, some sort of untextured, non-reflective dark material, such as a piece of black paper, should be placed behind the photo tank.
The artificial light source (strobe) can be hand-held at the top or side of the aquarium, or supported by some type of bracket. Transparent animals generally require only the use of one strobe unit since their bodies will not create a shadow. More opaque forms may require the use of strobes on two sides of the aquarium (or from the top). The result will be an image of a bright jelly against a black background, an effect that can be quite stunning.
A macro (close-up) lens (50 to 100 mm) with a single-lens-reflex camera (SLR) is generally the ideal photographic system to use. Whether you use automatic or manual exposure control is a matter of choice since excellent results can be obtained either way. Through-the-lens (TTL) exposures work well even with transparent jellies and permit less guess-work for proper exposure. You may wish to experiment with TTL settings to come up with those that work best for you. Manual exposure control will generally require some additional work to determine appropriate aperture settings for particular camera-to-subject distances. For a given distance, you may need to open the aperture a stop or two over what you might normally use for a more reflective subject. Bracketing exposures is advised to ensure that the correct aperture is covered. Focusing is best done manually by moving the camera back and forth until proper focus is achieved. Auto-focus systems tend to have difficulty selecting correct focus on transparent subjects like jellies. A small accessory focusing light permits focus control without contributing light to the image.
Entering the realm of gelatinous animals enables photographs to be made of them undisturbed within their natural environment. This can be done while snorkeling or with scuba, although its a bit easier to position yourself using scuba. Either housed SLRs or Nikonos systems can be successfully used. A housed camera permits more precise control of positioning of the jelly within the image, but requires excellent buoyancy control by the underwater photographer. Some photographers are more comfortable using a Nikonos camera, which is a viewfinder system that does not allow through-the-lens image viewing. For close-up photography a framer device with extension tubes is usually used with a Nikonos. This may present an advantage while at the surface or when back and forth surge is a problem.
Close approach to jellies is often easily possible since they generally do not react to your presence as would a fish. Care is still required since some, such as pteropods and heteropods, may swim away when disturbed. Most of the time you will want to be within 2 feet of the jelly unless photographing a large group. The delicate tissue of jellies can be easily damaged or destroyed by careless movement of water or release of air from your regulator. Try to avoid blasting air when you are underneath your photo subject since the large bubbles will send it rapidly to the surface.
A day with calm, clear water with few particles is obviously the best for photographing jellies while diving. Sunlight also helps since it can be used as a backlight to assist in illuminating the often transparent tissue. For relatively opaque jellies like Chrysaora or Pelagia the sun can be positioned behind the animal to give a nice backlighting effect that helps to show some of the internal structure. Light from a strobe (or 2 strobes, if you prefer) can then be used to fill in the front of the jelly. Highly transparent jellies pass an excessive amount of sunlight through, so you may need to position the sun out of the field of view. Strobe light may then be unnecessary if you can use light from the sun for illumination. By varying the position of the jelly in relation to the background light along with the aperture setting on the camera, you can determine whether the space around the jelly will have a black or more natural blue appearance in the resulting photograph.
Backscatter caused by reflection of light from particles in the water can be a problem. The bright spots that appear on the photograph can be very disturbing. Positioning the strobe so that it is angled between 45° and 90°from a straight-ahead orientation may help to minimize light reflecting back to the camera. This can also help illuminate transparent jellies. The idea is to reduce the amount of light that passes through the area between the jelly and the camera. Depending on whether you use small strobes or larger ones that cover a wider angle of view, you will need to experiment to find your own preferred positioning. You may also try using no strobe lighting and relying entirely on the sun as a light source. With their transparent or translucent tissue, jellies make fine subjects for natural light photography. Even if there are abundant particles in the water, they may not show up on the photograph with this technique.
Photographing large jellies generally requires a wide angle lens such as a 20 mm or 28 mm. This permits close approach while keeping the entire jelly within the boundaries of the image. Getting close is far better than using a normal angle or telephoto lens since it is desirable to minimize as much as possible the distance between the subject and camera when photographing underwater. Close-up photography for smaller jellies can be done with a SLR macro lens (housed camera) or extension tubes and framers (Nikonos). Close-up techniques can also be used on larger jellies to photograph fine details of the animal or some of the creatures that may be hitching a ride.