The 1.5x teleconverter (also known as a tele-extender) will multiply the focal length of the existing lens by 1.5x, and will cut back the amount of light by 1 f/stop. For example, using a 1.5x teleconverter with a 300 mm lens will effectively increase the focal length to 450 mm. A lens set to f/2.8 will now be f/4.
Teleconverters are not recommended for lenses wider than 50mm.
- Multi-coated elements result in crisper images