Bower 2x Digital Autofocus Teleconverter for Canon EF and EF-S Mount Lens

This 2x Digital AF Teleconverter contains 4 elements to ensure sharp imagery. This teleconverter utilizes multi-coated optics that will double the effective focal length of your EF or EF-S lens, for example it will convert an 85mm lens to 170mm. This doubling effect has a light loss of about 2 stops, meaning an f/1.4 lens will become an f/2.8 lens. Additionally, this teleconverter offers full communication between the lens and camera to enable autofocus and other electronically controlled functions.