Telephoto lenses

Telephoto lens is a very useful piece of kit in any photographers bag. The lens is useful in many ways, one - the most obvious is the ability to fill the frame with a subject that is far away, it's helpful in situations when you can't get close to your subjects, like a football game or wild animals.

Any focal length above 50mm can be considered as telephoto, say 70mm or 135mm etc. There are two types of telephoto lenses: prime lenses and zoom lenses. Prime lenses are lenses with fixed focal length. This means that the lens can't be zoomed in or out. This type of construction uses less elements and therefore less glass. Usually prime lenses are high quality, professional grade products and the maximum aperture is wider than in consumer lenses.

Zoom telephoto lenses allow you to change the focal length in the range the lens is constructed. For instance 70 - 300mm. These lenses are constructed using more elements than in prime lenses, therefore more glass is needed, and maximum apertures are not so wide as in prime lenses to keep the cost low. There are professional grade zoom lenses with wide maximum apertures, but they are very expensive bulky and heavy.

Other good way to utilize this type of lens is to use it in portrait photography: use the long end of the lens (150 - 300mm) and a wide aperture (f5.6 or wider), place your sitter some distance away (the farther, the more blurred the background will be) from the background and focus on the eyes (the closest eye to the lens if the subject is turned). This technique will give you portraits with nicely blurred backgrounds and shallow depth of field.

Another use is in close-up photography, like flowers and other small objects. Long lenses compress perspective in the images compared to wide angle ones, if you will take a picture of telegraph poles from a side angle with a wide angle lens they will appear much apart, but if you will use a telephoto lens instead and frame the scene the same way as previous (you'll have to stand farther because long lenses bring everything closer) the poles will appear kinda compressed and closer to each other. Lenses are tools you can use creatively to achieve the incredible shots you're after.