The EF 400mm f/5.6L USM lens is a cheap and low weight super telephoto prime lens released for several years ago. Recently, according to CR, it is mentioned that Canon is workong on a new EF 400mm f/5.6L IS USM lens.
This new IS version lens will be announced in 2016. The weight of this new lens will be reduced, and the price will also not be very expensive. This lens is designed for bird shooters.
Read More: Canon Rumors