Canon will be officially announcing an RF 400mm f/2.8L IS USM super-telephoto lens. This lens is optically identical to the EF 400mm f/2.8L IS USM III. I do wonder if this and the RF 600mm f/4L IS USM will be stopgaps while Canon designs new super-telephoto lenses to take full advantage of the RF mount.
The Canon RF 400mm f/2.8L IS USM will launch at $11,999 USD.
Below is official Canon information about the RF 400mm f/2.8L IS USM.
High-performance, Wide-aperture 400mm f/2.8 Super-telephoto Lens, Exclusively for EOS R-series cameras
Inheriting the optics of the EF 400mm f/2.8L IS III USM, the same high image quality is maintained in the RF400mm F2.8 L IS USM with outstanding sharpness and contrast, center to corner, even at maximum aperture. A combination of Fluorite and Super UD (Ultra-low Dispersion) glass is at the heart of this lens’s outstanding optical performance. At the widest aperture of f/2.8, chromatic aberration is significantly reduced, to achieve tack-sharp images with minimal color fringing. This means detailed results in any shooting condition, particularly in low light levels.
Optically Identical to EF 400mm f/2.8L IS III USM lens
The latest EF version of the 400mm f/2.8L IS lens, introduced in late 2018, preserved the legendary sharpness of previous EF400mm f/2.8L lenses, but with a dramatic reduction in overall weight. The RF version, dedicated to EOS R-series cameras, preserves this advantage, providing outstanding handling for a super-tele lens with an f/2.8 maximum aperture. Numerous optical and mechanical steps combine for this supremely light weight, transforming the RF400mm F2.8L IS USM into a lens that’s equally at home in situations requiring mobility and portability — such as motorsports and wildlife — as it is fixed on home plate at a night baseball game. And, since it uses the same optical design as the EF version III lens, the same superb image quality can be expected.
Optical Image Stabilization with up to 5.5 Stops of Shake Correction, Including Three IS Operation Modes
The RF400mm F2.8 L IS USM features an Optical Image Stabilizer system that provides up to 5.5 stops of shake correction, delivering consistent and sharp results. Whether hand-held or mounted on a monopod (or other devices allowing mobile positioning), the lens’s Image Stabilization can deliver clear image detail in low-light situations or at lower ISOs. This applies when capturing both stills and video, for stable shooting, and sharp final imagery.
Three IS Operation Modes
Three image stabilization modes provide shake-correction for outstanding results in a wide range of shooting situations. These include traditional stabilization, with the correction visible any time IS is active in the camera’s viewfinder (IS Mode 1); helping to correct camera shake when intentionally panning horizontally (or vertically), providing shake-correction perpendicular to the photographer’s panning movement (IS Mode 2); and stabilization that instantly goes into effect only when the shutter is released — no correction visible between shots, in the camera’s viewfinder (IS Mode 3).
Super Spectra Coating (SSC) and Air Sphere Coating (ASC) Helps Minimize Ghosting and Flare
The RF400mm F2.8 L IS USM lens features Canon's Super Spectra Coating (SSC) that helps maintain overall image quality and color fidelity, as well as Air Sphere Coating (ASC), which significantly helps to reduce the occurrence of lens flare and ghosting. The RF400mm F2.8 L IS USM continues to deliver outstanding images and video, even at maximum aperture, in harsh back-lighting conditions.
Compatible with Canon RF 1.4x and 2x Extenders
To help get you even closer to the subject, attach the compatible Extender RF 1.4x or Extender RF2x to the RF400mm F2.8 L IS USM. Expand effective telephoto power to 560mm at f/4 with the Extender RF 1.4x, or to effective 800mm at f/5.6 using the Extender RF2x. The extenders allow even more telephoto reach when it’s needed, yet allow the user to convert back to an f/2.8 lens for low-light situations by simply removing the extender.
Customizable Electronic Focus Ring, with Manual Focus Capability during SERVO A
The lens’s large manual focus ring is located directly on the lens barrel, and allows you to select from three different manual focus speed levels, to adjust the focus ring rotation to your desired preference. The “1” position on the M.Focus Speed switch provides the fastest sensitivity (a small amount of focus ring rotation provides significant focus change in the lens); settings 2 and 3 reduce this sensitivity, allowing for finer manual focus adjustments.. This can help whether you need a slow speed to switch between someone’s eyes in a distant profile, or a fast speed to dial in on different birds in a large, swiftly moving flock. Additionally, depending on camera settings, manual focus is still possible while AF is engaged, letting you fine tune focus adjustments to suit your shooting preferences.
9-blade Circular Aperture for Beautiful Bokeh
Thanks to its 9-blade, circular aperture, the RF400mm F2.8 L IS USM is capable of gorgeous, evocative out-of-focus areas and soft backgrounds. With rounded rendering of background blur, the 9-blade circular aperture helps create intimacy and intensity in both photos and videos for impactful results.
Two Focus Presets Available — Instantly Return to One or Two Memorized Focus Distances
Quickly select between one or two memorized focus distances, with focus presets. Especially useful for fixed-position sports photography, you can focus upon and memorize two separate focus distances. Then, with a simple twist of the playback ring, immediately jump back to one or the other. A sports photographer, for example, could easily pre-focus on home plate and 2nd base at a baseball game, with the ability to rapidly move focus back to either position with a slight turn of the playback ring on the lens barrel.
Dust- and Water-resistant Design, with Fluorine Coating on Front Element for Easy Cleaning
Built to L series lens specifications, the RF400mm F2.8 L IS USM features a highly durable design for excellent performance even in inclement weather conditions. It delivers a dust- and water-resistant construction with seals around the mount, switches, rings and more. To help maintain a clean lens, even after multiple lens changes in sub-optimal conditions, the RF400mm F2.8 L IS USM has a specially designed fluorine coating on its front and rear surfaces. The coating helps to prevent water, oil and other surface residue like fingerprints from sticking to the lens, which facilitates quick and easy wiping, without the use of solvents.