Canon's latest lens isn't one that most of us will own, or even get to use. But pros who make a living shooting sports, fashion, events, and wildlife should find some utility in the RF 100-300mm F2.8 L IS USM. It's not exactly the first zoom of its kind—Nikon and Sigma both made 120-300mm F2.8 lenses for SLRs—but Canon still wins a first-ever prize for stretching the wide angle to 100mm, and making the lens for a mirrorless system.
A Zoom for the Pros
As an L series lens, the 100-300mm has all of the accouterments you expect. The zoom is fully weather-sealed, with water-repellant fluorine on the front glass. It includes a full control panel of switches and toggles on one side, and has a rotating tripod collar. At 5.8 pounds and 12.7 inches long, the lens may not be handholdable for every photographer. The tripod foot is not made for Arca-Swiss tripod heads, though, so you'll need to add a quick release plate.
The 5.8-pound weight may sound heavy, especially for enthusiasts used to carrying a lens like the 3-pound RF 100-500mm, but it's not too much more than the 5.3-pound EF 300mm F2.8 prime for Canon SLRs, and a less than the Nikon 120-300mm F2.8 (7.2 pounds) or Sigma 120-300mm F2.8 Sports (7.5 pounds).
The extra weight comes from the F2.8 optics. Opening up to F2.8 creates more separation between subject and background, an aspect aided by a telephoto length. Canon can make the RF 100-500mm so light because it gathers light from F4.5-7.1 across its range, a formula that requires less glass to imagine.
The RF 100-300mm F2.8's optics include 23 elements arranged in 18 groups, including the massive front element. Focus is driven by dual USM motors, which promise great speed, though we'll note that we've not had a chance to test the performance ourselves. There's no support for rear drop-in filters with this one, so you'll need to reach for expensive 112mm filters if you want to add ND or a circular polarizer.
Stabilization is rated for 5.5 stops on its own, and stretches to 6.0 stops when paired with an R camera with IBIS. Other features of note include a preset focus function, an on-barrel control ring, and on-lens function buttons. The zoom is also compatible with the two RF teleconverters; with the 1.4x extender it becomes a 140-420mm F4 and with the 2x it's a 200-600mm F5.6.
A Zoom to Replace a Prime?
In its marketing material, Canon is selling the RF 100-300mm F2.8 as the replacement for its customers who'd previously used the EF 300mm F2.8 and are looking for a more versatile solution for an R series camera. It certainly appears so in concept; being able to back out to a wider angle may very well turn an occasionally used prime into a zoom that gets more time.
We've not seen any 300mm F2.8 lenses for full-frame mirrorless to date. Even Sony, which has been making FE lenses for its mirrorless system for a full ten years, has only made a development announcement for one, coming next year. We'll have to wait and see how it stacks up in size, weight, and price, versus Canon's zooming approach.
The RF 100-300mm F2.8 L IS USM is available for pre-order today for $9,499 and is expected to start shipping in May.