I took this picture in 1995 on my second trip to the Galapagos Islands. My medium format camera at the time, the Mamiya RZ 67, gave me very sharp images but the depth of field was less than what 35mm cameras offered. The reason is that the equivalent lens aperture -- say f/8 -- on a medium or large format camera is physically larger than it is on a 35mm camera (and a full frame digital format camera as well). These marine iguanas were sunning themselves in the morning on lava that had a slope to it. I positioned the camera such that it was aimed downward, and that made the angle of the reptiles oblique to the film plane. That, in turn, created a depth of field headache, so to speak. I needed the entire scene sharp, so the only way to get that was to use f/32. The small aperture forced the shutter speed to be one full second at ISO 100 (I was using Fujicrome Provia 100 slide film). Fortunately, when reptiles are cold, they remain perfectly still. I shot this from a tripod, thus I was able to capture a tack sharp image. I used a Mamiya 110mm lens, which was equivalent to a 50mm focal length in the full frame digital format.