Underwater Photography in Key West, FL by André Costantini
While testing the Tamron 17-50 f2.8 in Key West, I had the opportunity to take it underwater. I had procured an EWA Marine underwater housing for my digital SLR and figured that was a perfect excuse to try diving. As I had never dove before and I wasn't about to spend my entire week getting certified, I opted for the resort dive. A resort dive is an assisted dive where basically you get an hour pool class, learn the basics and then a couple of hours later you find yourself 60 feet underwater looking at morays and such. The first dive was spectacular. Now at 60 feet underwater you are dealing with more then twice the atmospheric pressure that you would on land. The EWA housing is a soft plastic housing that keeps your digital SLR airtight underwater up to 66 feet. Having never done any of this before (diving, underwater photography or used this housing) I got to witness the visual impact of that pressure when I noticed my camera was vacuum packed in that housing so tightly that it wasn't even possible to press the shutter release. (Now I understood what that valve to add air was for.) So you'll have to take my word on that moray eel.
Living and learning I met with slightly more success on the second dive. First of all it was only 30 feet and second of all I added air to the housing.
Because of the characteristics of water on the optical world, I left the camera in auto focus and taped the lens to stay at the 17mm focal length. Lenses appear to be 1/3 less wide down there. As it turns out, objects appear 1.33 times larger underwater, and the focusing distances under water are different then on land. Interestingly, your auto focus will work and if you manually focus, this will also work. However if you measured the distance from your camera to the object you were photographing and then you matched the focus distance on your lens, the object would not be in focus!!! Regarding exposure I just left the camera on Program mode. There were far too many factors as it were, plus the light levels significantly change from near the surface to 60 feet below. Though the housing will accommodate a flash, my dive master suggested that images with flash often just illuminate the scatter in the water. There are specific lighting rigs for diving if you are a professional which take these factors and angles of light into account. I just used the available light to illuminate these seascapes. Using the Tamron 17-50 on this trip was great. It allowed me to have a wide enough angle lens to photograph underwater and then rise to the surface and use the fast 2.8 aperture to capture the glorious sunsets Key West has to offer. |
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