The 55-200mm f/4.0-5.6 DT Alpha A-Mount telephoto zoom from Sony is has a 55-200mm focal length. For this DT-series lens, that’s like having a 82.5-300mm telephoto lens in 35mm terms. It helps you shoot from a distance, so its a good tool to pack for things like wildlife tours where you might be spotting a tiger in the distance and want to see and capture it as if close up. It is also used for capturing events like sports games or concerts. This 55-200mm Alpha A-Mount telephoto zoom lens by Sony has been optimized for cropped image sensors, and this means it is ideal for certain smaller cameras rather than large full-frame ones. Essentially, it has been designed for APS-C-sized sensors used in many Sony Alpha DSLRs, because they have SteadyShot INSIDE image stabilization built in. For that reason, they take more compact and lighter lenses. Specifically, it was made for APS-C Size / DT-Format Alpha & Minolta digital SLR models and is not recommended for full-bodied large devices because you would be doubling up on mechanics and unnecessarily increasing the weight of your kit. It effectively has your desired focal length when you use APS-C-sized units, with a varying length aperture that’s fully dependent on the length chosen. For example, you can increase from f/32 to 45 or f/4.0 to f/5.6, depending on how much you increase the zoom. Using it at its mid-length you can work on some creative bokeh effects, with sharp subjects and softened surroundings. You can also capture close-ups, with a minimum focusing distance of 3.2 feet and a front-end filter diameter of 55mm. Another important specification is its 7x circular aperture blades, which produce seamless movement and let you create blurred background effects around your crisp subject. This lens comes equipped with a SAM, also known as a Smooth Autofocus Motor. This effectively gets rid of the need to use mechanical coupling within the camera body itself. No longer does drive power have to be transferred directly to the lens. Instead, the control signals transfer from the body to the SAM unit. This may sound complicated, but the end result is more precise, crisper photographs. Whether you are shooting in low light or bright conditions, with or without a filter, this lens performs to your expectations and shows beautiful results too. Dispersion glass is another feature on this lens. This low-light glass corrects certain waves of light when the camera is working at over 300mm, and this dramatically reduces the occurrence of chromatic aberrations. As well as being a practical and thoughtfully designed telephoto lens for specific cameras, the Alpha A-Mount by Sony is well made. It is constructed of 13 elements in 9 groups, as well as extra-low dispersion (ED) glass, which all help to deliver sharp, clear photos throughout the range. It weighs 10.41 oz. This is a well-thought-out piece of photographic equipment from Sony that goves high performance and is more practical to carry in your kit (providing you own the right camera with in-built stabilization) and extends a photographers love of the art and the quality of his images.