Japanese site Egami seems to have discovered a Canon patent filing detailing a replacement for its 17-40mm F4 L USM zoom lens.
Sporting a brighter F2.8 to F4 variable aperture range, the new lens could enable users to capture sharper images in low-light conditions, due to a brighter F2.8 aperture at its 17mm wide end. This provides a one-stop improvement over its predecessor.
The Canon 17-40mm F4 L USM lens has always been one of Canon's most popular lenses, thanks to its constant F4 aperture and its ability to capture an ultrawide-angle perspective, when used on a full-frame camera. It is also the cheapest premium L lens currently available.
Details are scant, at this point, but we will keep you updated, when we have more information.