LOCALadk Magazine
Issue link: https://localadkmagazine.uberflip.com/i/377278
Fall 2014 53 LOCALadk they really are, and they usually require faster shutter speeds or use of a tripod to avoid camera blur. As a rule of thumb, the camera's minimum shutter speed should be equivalent to the lens focal length. For example, for a lens focal length of 200mm the minimum shutter speed should be 1/200th of a second. The educational resources available for learning more about how lenses work are endless. A quick Google search of "How a lens works" revealed approximately 77,000 items. A resource that I use often is a free app called "Depth of Field Calc". This app provides me with the hyperfocal distance (area of critical sharpness) for a given focal length, at a given f-stop. That is the area in front of and behind my subject that will be rendered reasonably sharp. I preset the app for my camera (this way it knows whether it is a full frame or cropped sensor), then I enter the distance my subject is from the camera, the f-stop I have chosen, and my focal length. It then provides me with the hyperfocal distance. I would also recommend that you go out and shoot the same scene at varying focal lengths and also shoot various objects that are a reasonable distance from the background at different focal lengths and different f/stops. Download the images to your computer and study what is going on in the scene. Note which settings you feel captured the image best. I recommend that you continue this process until you grow proficient in visualizing a scene the way your lens will render it. Great Blue Heron Rookery: For this image, great care was spent positioning myself so I would have a clean background, an unobstructed view of the nest, and enough room to capture an unobstructed view of the adult's flight path. I predetermined the exposure difference between the nest area and the flight path so I could quickly change my settings without thinking about it when the action occurred. With wildlife photography, many hours are spent waiting for that quick moment of action. Based on a few test shots, I preselected an f-stop of 7.1, as I knew this would leave the nest and its occupants reasonably sharp while giving me a pleasing background. (Nikon D4, 600mm lens, 1.4 tele-converter, ISO 1250, f7.1, 1/800th sec.)