The Lens Choice You Make Will Define Your ImagesLens choice is, in my opinion, much more important than the camera body, whether SLR or compact. Optical quality and focal length control the image to a larger extent than the size or the format of the film or digital sensor. The lens is the piece of photography equipment that deserves the most thought and consideration and often the largest portion of the equipment budget.
Lens Choice 2
Telephoto Lenses Provide Solutions And Introduce Problems
Telephoto lenses solve many problems for photographers. The narrower angle of view and shallower depth of field they provide can exclude distractions from a background. Their magnifying power can provide frame filling shots of shy nature subjects from a distance. The tight field of view can provide a “stacked” perspective of distant objects not possible with shorter focal length lenses. These very useful properties, of course, come with trade-offs as do all lens choices. Because, by definition, telephotos have longer focal lengths, they must to some degree be physically longer as well. With lens aperture defined as a ration of lens focal length, maintaining a given aperture means a larger diameter lens as the focal length increases. Again this makes a physically larger lens. And maintaining large apertures are more important as focal length increases because shutter speed must increase with focal length to maintain image sharpness when hand holding. This usually amounts to the best telephoto lenses for overall image quality being the largest and heaviest(least portable), while the easiest telephoto lenses to carry around with you have the most photographic compromises. I have been using a camera regularly with telephoto lenses since the early 1970’s. Many things have changed during that time, including major changes in lens design. I have also been able to slowly revise and refine my personal working lens collection during this time. My lens coice is basically a double set of lenses from “normal” through “telephoto” range: one set for bright daylight walking/hiking that is small, light, slow and relatively cheap and a second set for low-light conditions that is large, heavy, fast and expensive. Both sets provide approximately the same image quality, but the faster lenses tend to keep that quality at their wide-open apertures while the slower lenses do best when closed down a stop or two, further compromising their speed. The faster lenses are about twice the size, three times the weight and four times the price of the slower lenses. My current choice of short/fast lens is a 28mm-105mm with a constant f2.8 aperture that is 8” long, weighs 2 pounds and takes a 82mm front filter. The long/fast lens choice is a 70mm-200mm with a constant f2.8 aperture that is 12” long, weighs 2 ½ pounds and takes a 77mm front filter. The short/slow lens is a 18mm-70mm with f4-f5.6 variable aperture, is 3” long and weighs just over 7 ounces. My long/slow lens choice is a 75mm-300mm with f4.5-5.6 variable aperture at 7” long and 12 ounces. Both slow lenses take 55mm front filters. This means that during the middle of the day I can carry a camera with either slow lens mounted and only need a small fanny pack for the second lens and other necessities. During low light times with the fast lenses, I need my photo backpack or a large second waist belt dedicated to a lens. The fast lenses retail around $1,000 each while the slow lenses are less than $200 each. This is a very big difference! Another compromise introduced by any longer lens is camera vibration and motion. Just as with binoculars, as lens magnification increases it increases lens(camera) motion. While the internal vibration caused by the reflex mirror is not usually a factor with lenses less than 150mm, it is a significant factor with lenses over 300mm. I regularly use lenses up to 400mm, sometimes with a 2x teleconverter. I always mount these longer lenses on a tripod, use an electronic shutter release, lock the mirror up if possible and avoid shutter speeds between ½ and 1/30 second(where mirror vibration is worst in most camera bodies). If using the teleconverter to achieve focal lengths over 400mm, I also drape a rice-filled bean bag across the top of the lens above the tripod mount and see a marked increase in sharpness. Another sharpness enhancer with long lenses in to use the least possible tripod extension. This works well for most nature photography as it puts the camera closer to eye level for most animals and plants. Working with minimal tripod extension, especially avoiding extension of the center column, minimizes vibrations within the tripod that can be passed along to the camera during exposure. Extending the center column creates a monopod on top of the tripod. Hanging a photo pack or other weight from the tripod can also add extra stability, particularly when it is windy. You should shoot several series of test exposures with any new telephoto lens you buy. Vary things like the tripod extension, shutter speed, remote release or not, mirror locked up or not, etc… to see when the sharpest images result. Also do this for each camera body, as mirror vibration varies with camera models and brands. You will not always be able to shoot at the sharpest settings but you will know to shoot extra exposures in the hopes of getting a few good ones.
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