A teleconverter lens addition gives a camera two times as much zoom. For the Nikon D300, you have a choice of teleconverters that apply different degrees of focal length and extension. As of 2011, Nikon sells three specific lenses that likely provide the best compatibility with your camera and its warranty.
Considerations
Teleconverter lenses attach to the lenses you currently use with your Nikon D300, with certain limitations. If your lens has an F-stop of 4 or higher, a teleconverter lens typically will be incompatible because the quality isn't good enough. Also, large zoom lenses, such as 200mm to 400mm models, can't connect to any teleconverter lens, except for the TC-14E II lens.
TC-17E II
One of the smallest lenses is the AF-S Teleconverter TC-17E II, which increases the magnification by 70 percent, according to Nikon, and has built-in auto focus. This teleconverter will provide extra zoom without lowering the quality of a photo as much as larger lenses. As of November 2011, it retails for $550.
TC-14E II
Weighing a little over 7 ounces, the AF-S Teleconverter TC-14E II is a teleconverter that provides a 40-percent zoom increase onto the attached lens. Priced at about $520, the lens proves an ideal first teleconverter for Nikon camera owners. Its small size simplifies travel and allows easy extension of zoom during sports events or when trying to capture nature.
TC-20E III
The AF-S Teleconverter TC-20E III features the largest focal length extension. Its "2x" teleconverter will double the focal length of your lens, but also degrades it by two F-stops. This means that if you have a 1.8 lens, you cannot adjust the aperture to anything wider than a 3.8. The lens costs about $500.
Tags: AF-S Teleconverter, focal length, Nikon D300, teleconverter lens, focal length extension, length extension