The 2x DG Teleconverter (also known as a tele-extender) will multiply the focal length of the existing lens by 2x, and will cut back the amount of light by 2 f/stops. For example, using a 2x teleconverter with a 300 mm lens will effectively increase the focal length to 600 mm. A lens set to f/2.8 will now be f/5.6.
This DG teleconverter has upgraded "Gate-Array IC" circuitry to work better with digital SLR's and some of the digital SLR lenses*. This means that the converter's unique circuitry maintains signal integrity between the camera body and lens.
Teleconverters are not recommended for lenses wider than 50mm, e.g. 28-105mm. However, full AF operation is only possible with lenses with open aperture of f/2.8 or brighter. Please be aware that AF will work properly only if there is enough light and contrast on the subject to activate the camera's AF sensors. Manual focusing is recommended when using lenses with smaller open f-stop value than those given above.
Note: Not compatible with the Canon Digital-only EF-S lenses, e.g. 18-55 f/3.5-5.6, 17-85 f/4-5.6, 60 f/2.8 macro.
