CPN article here. Description and specs:
The EF 400mm f/4 DO IS II USM lens delivers brilliant high-speed performance for professionals with minimal glare and superb image quality. Taking advantage of the best in lens technology, it features gapless dual-layer diffractive optical elements for improved diffraction efficiency with reduced flare. These elements are arranged with a large-diameter ground aspheric lens and a UD lens for a new level of sharpness and clarity. New coatings help to reduce ghosting, ensure excellent color balance and reduce fingerprints on the front and rear of the lens.
Professional L-series dust- and water-resistant construction is complemented by impressive performance: a 3 mode Image Stabilization system offers up to four stops of compensation and can even prevent operational errors when the camera is mounted on a tripod. AF stop buttons placed on the front of the lens can automatically stop focusing at any time; full time manual focus ensures complete control no matter the AF mode, and a Power Focus (PF) mode makes for smooth focus transitions when shooting movies. The EF 400mm f/4 DO IS II USM focuses down to 10.8 ft. (3.3 meters), has a 9-blade aperture for pleasing, soft, out-of-focus areas, and is constructed with environmentally friendly lead-free glass.
- Compact, lightweight super telephoto lens that is ideal for sports and wildlife photography.
- Newly-developed gapless dual-layer diffractive optical elements deliver improved image quality with reducedvflare.
- Large diameter ground aspherical lens and UD lens for even greater optical performance.
- Optical Image Stabilizer provides up to four shutter speed stops of correction*.
- Three image stabilization modes (standard, panning, and during exposure only) provide exceptional results for a wide range of shooting situations.
- For greater convenience, Image Stabilizer does not have to be disabled when shooting with a tripod.
- AF stop buttons on the front of the lens allow you to stop autofocusing at any point.
- Optimized lens placement and coatings deliver exceptional color balance, while minimizing ghosting and flare.
- Highly resistant to dust and water, enabling shooting even in harsh conditions.
- Circular aperture (9 blades) delivers beautiful, soft backgrounds.
- Full-time manual focus allows manual focus adjustment while in AF Mode.
- Power Focus mode enables smooth focus shifts essential for filmmaking.
- Fluorine coating on front and rear lens surfaces reduces smears and fingerprints.
- Minimum focusing distance of 10.8 ft./3.3 m.