GET TO KNOW TELEPHOTOS
Long optics are loaded with advanced features
Just as ultra-wide lenses are required for stretched perspectives, frame-filling shots of far-off subjects cannot be achieved without the use of telephoto optics. Whether you select a long telephoto prime lens, such as a 500mm f/4, or a telephoto zoom, like a 70-300mm f/4-5.6, these models enable the photographer to refine their composition precisely, cropping out unwanted environmental detail. Equally, for portrait images or some landscape scenes, using a longer focal length can compress perspective, appearing to bring the background closer and reducing distortion of facial features.
These lenses are usually the choice of wildlife and sports photographers – most notably models with focal lengths of above 300mm. For this reason the features incorporated into telephotos are usually geared towards allowing rapid work – quickly achieving focus and enabling nearinstantaneous recomposition.
Due to the higher magnification, camera shake is also a far greater probability when using telephoto optics, so professional models almost always make use of image stabilisation technology. This makes handheld shooting in lower ambient lighting a possibility, by varying the position of specialised lens elements to counteract camera shift. The effectiveness of this system varies from lens to lens, although most contemporary stabilisers enable up to three stops of shake reduction as a minimum.
On more advanced lenses you will find additional speed-beneficial features, such as supersonic wave autofocus motors, internal and rear-focusing mechanisms, and the ability to apply manual focus adjustments at any time, even if AF is active. While these may not be worth the extra investment if you rarely shoot in extremely fast-moving scenarios, for working pros and advanced enthusiasts they can mean the difference between grabbing a shot and missing a winning opportunity.