Help Prevent flare Designed for 17-85mm f/4-5.6 IS EF-S and 18-135mm f/3.5-5.6 IS Lenses
The addition of a lens hood can help prevent flares-
those circles of light that can accompany images where a strong light source is just outside the fame
These type of lens flares occur when indirect light rays pass through the front lens elements but don't make it all the way through to the image sensor.
Technical Detail
Package Height 2.4 x 4.2 x 4.3 inches
