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|1:1 and Beyond
Tools and techniques for photographing the reef’s tiniest subjects
Text and Photography by Stephen Frink
I was recently on assignment in St. Vincent at a time when the rainfall had been rather extreme. Of course, I had just left Hurricane Wilma in South Florida, so a little bit of rain didn't seem such a bad thing in comparison. But it did step on the water clarity in a destination that normally offers terrific wide-angle opportunities. So I retired my 17-40mm zoom and 15mm fisheye for a week and concentrated on the world of macro, specifically at ratios of 1:1 and beyond. Fortunately, I was in the perfect destination for such an exercise, as St. Vincent also offers some of the best small-critter diving in the Caribbean. Here are some observations to make an excursion into super macro more productive.
Any of these lenses can focus from infinity to 1:1 (life-size). Other popular optics include the 200mm Micro-Nikkor and the 180mm macro from Canon, each offering 1:1 from a significantly greater distance. However, given their shallow depth of field and the housing modifications often necessary to use them, these are specialty lenses. Actually, in the world of super macro, even the 50/60mm lenses (full-frame) are difficult because minimum focus is achieved so close to the primary subject. This may spook the subject, and it certainly makes it tough to get the strobe light where needed, without a shadow from the front of the port. With the 50/60mm macro lenses and some close-up accessories, the minimum focus falls inside the front glass of the port, making it impossible to use. For the purposes of this article, I'm talking about the 100/105mm macro lenses, although a 60mm Micro-Nikkor on a D2X with a 1.5 crop is essentially a 90mm lens, so some of the discussion is relevant there as well. Yeesh! Now even I'm confused.
The lens's native magnification will deliver life-size imaging, but getting great magnification will require some kind of accessory, such as a teleconverter, extension tube or diopter (close-up lens).
Teleconverter: Maintains the working distance of the lens, but at the cost of light transmission due to additional glass elements. A 50mm f-2.8 lens with a 2X teleconverter becomes essentially a 100mm f-5.6 lens, but it is capable of capturing twice-life-size images. Some teleconverters allow autofocus, but it is exceedingly difficult to use autofocus with such narrow depth of field. Ideally, the housing should allow a special port with a manual focus knob, which then would mate with the lens focus gear. If I had to choose autofocus or manual focus with a teleconverter, I'd opt for the manual focus.
Extension tube: The extension tube has no glass inside, but does move the lens farther from the sensor plane, thereby shifting the focus range. For example, with the Canon 100mm macro lens, Canon's EF25II extension tube has a very limited focus range, probably between six and 12 inches. Anything closer or farther away than that will not be in focus, but with the right subject this can be a sweet option. Again, a special port that allows manual focus gives considerably more control. With either a teleconverter or extension tube installed, you'll be in super-macro mode for the duration of the dive.
Diopter: A diopter is simply a close-up lens that screws onto a lens's front thread. For topside use, this is a simple, inexpensive and easy solution. However, for underwater use, adding a +4 diopter to your 100mm macro lens (as I've done often in the past for dives dedicated to pygmy seahorses) is fine as long as you only want to shoot tiny creatures on that dive. A far better solution is to use a wet diopter, a close-up lens that fits over the port. This allows the normal “infinity to 1:1” from the 100mm macro lens, yet you can add up to twice-life-size imaging simply by adding the wet diopter to the front of the port, while under water. This is the only option that permits normal reef photography in conjunction with super macro on the same dive.
MacroMate: Greatest magnification of available wet diopters with achromatic lens design. (www.backscatter.com)
Woody's diopter: Popular and inexpensive external diopter designed to fit a variety of housings. (www.nexusamerica.com)
Seacam diopter: Made only to fit Seacam macro ports, available in two different magnification strengths. (www.seacamusa.com)
Normally, I would use the built-in model light from my strobe, but I've noticed that halogen bulbs, which are fine autofocus assist lights for subjects three feet away, tend to scare subjects away when I'm working at the small distances required of super macro. This makes sense when you consider both the intensity and heat emitted by these bulbs. Many model lights are now using LED lights, which produce less heat and offer far greater burn time per set of batteries. The new Ikelite DS-80 has a built-in LED model light, and I expect this technology to be the trend of the future. On the St. Vincent shoot, I used a beautiful model light by Nocturnal Light (www.nocturnallight.com) with an articulated ball joint to more easily aim, and a diffuser to soften and spread the beam.
Of course, the hardest part of super macro is finding the subjects, and to that end a thorough knowledge of marine biology can help you understand where the creatures are located and why they happen to be there. Once you understand the environments and inhabitants, the creatures are much easier to find. For me, that means a close-up lens in my mask as well. I also find that a wet diopter serves as a pretty good magnifying glass when scouring the reef for tiny, cryptic creatures. Still, it is no secret that the very best way to find the reef's most fascinating super-macro subjects is with a talented and intuitive local guide. Many of these critters are relatively sedentary, so the guides learn where they are likely to be found and can deliver sightings consistently. Even with fortuitous random sightings, it helps to have an extra set of eyes scouting for the next photo op while you are occupied with the current setup. Is it cheating? I don't find it much different from going on safari with an experienced guide in Botswana--the best guides are the ones who can find the animals, and then position the photographer for the best compositions. In either case, appreciate their talent, and reward them generously.
To Autofocus or Not
Most modern digital SLR cameras offer multiple zones of autofocus and lenses that are very efficient at snapping into focus. However, the shallow depth of field of super macro makes manual focus often the better solution. I like to use autofocus for bold subjects like the eye of a peacock flounder, whereas the minimal depth of field and erratic motion of animals like shrimp or blennies make it easier to rack the lens to minimum focus on manual, slip on the wet diopter, and then just creep forward until the fish pops into focus on the ground glass.
Ideally, the housing will offer both autofocus and manual focus options with the macro lens, but if I had to choose one or the other (and with some housings you'll be forced to), with the 50mm lens I'd opt for autofocus, while with a 100mm, most subjects will be better served with manual focus.
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