Canon RF 28-70mm f/2 L USM Review
The RF 24-70mm f/4L IS USM is designed to be the ultimate standard zoom lens for Canon's full-frame mirrorless camera system. This lens offers the versatility of a zoom combined with the fast maximum aperture of a quality prime - it's the only standard zoom lens that we've ever reviewed with a maximum f/2 aperture.
Comprised of 19 elements in 13 groups, including four aspherical elements, a pair of Ultra Low Dispersion (UD) elements and a Super UD element, the RF 28-70mm f/2 also features an Ultrasonic Motor for quick and quiet auto-focusing, fluorine coatings on the front and rear lens elements, SWC and ASC coatings to help reduce ghosting and flare, 9 rounded diaphragm blades for smoother bokeh, a zoom lock switch to prevent lens creep, and weather-resistant construction.
The new Canon RF 28-70mm f/2 L USM officially retails for £3079.99 / $2999.99 in the UK and the USA respectively.
Ease of Use
The Canon RF 28-70mm f/2 L USM is a large and very heavy lens, considering the rather modest focal range that it covers, weighing in at a whopping 1430g and measuring 14cm in length, extending further to 16cm when the lens is set to 70mm. It's best to think of this lens as four high-quality prime lenses in one, rather than just as a standard zoom, in which case it makes more sense from a size point of view.
Build quality is superb. The Canon RF 28-70mm f/2 L USM feels like a tank in your hand, even if the exterior is mostly made out of plastic, and it features enhanced resistance to shock and vibration and weather-proofing too.
A new feature for RF lenses is the Lens Control Ring at the end of the lens barrel, which can be used to control certain key camera settings. Although not a new concept in the wider photography world, this is the first time that Canon have incorporated this idea into their interchangeable lenses. You can use this to change a variety of settings including aperture, shutter speed, ISO and exposure compensation.
The Canon RF 28-70mm f/2 L USM does not feature Image Stabilisation, instead relying on its fast aperture of f/2 top help when shooting in low-light. It's worth noting that virtually all other top-of-the-range zoom lenses typically offer a maximum aperture of f/2.8, a whole stop slower than the RF 28-70mm f/2 L USM, which is one of the principal reasons for the size and weight of this lens.
The Lock function switch is a useful feature that helps protect the Canon RF 28-70mm f/2 L USM lens. Set the focal length to 28mm and move it to the Lock position to prevent the zoom mechanism from creeping when the camera is pointed down or in storage.
The final control on the lens barrel is a focus mode switch with the usual AF/MF settings. Note that this lens usefully offers full-time manual focusing even when AF is selected.
The focusing ring is wide enough to find easily, and it has a ridged, rubberised grip band. There are no hard stops at either end of the range, making it more difficult to set focus at infinity. Polariser users should be pleased that the huge 95mm filter thread doesn't rotate on focus.
When it comes to auto-focusing, the Canon RF 28-70mm f/2 L USM zoom is a very quick performer, taking around 0.10 seconds to lock onto the subject when mounted on the Canon EOS R camera that we tested it with.
We didn't experience very much "hunting" at all, either in good or bad light, with the lens accurately focusing virtually all of the time. It's also a pretty quiet performer, thanks to the built-in USM (Ultra Sonic Motor).
The Canon RF 28-70mm f/2 L USM lens ships with a plastic, petal-shaped lens hood (EW-103E) and a soft drawstring pouch (LP1424). Given the asking price, we'd have liked to have a better case included.
At the 28mm focal length the angle of view is 65 degrees.
At the 70mm focal length the angle of view is 29 degrees.
Chromatic aberrations, typically seen as purple or blue fringes along contrasty edges, are very well controlled with the Canon RF 28-70mm f/2 L USM - so much so that we couldn't find any examples at all in our test shots.
With the Canon RF 28-70mm f/2 L USM lens wide open, you can only see a little light fall-off in the corners at both ends of the zoom range. Stopping down helps, although to completely get rid of this phenomenon, you will need to use an f-stop of f/4 or smaller.
Barrel distortion is slightly evident at the 28mm wide-angle focal length, but it disappears completely by 35mm.
The Canon RF 28-70mm f/2 L USM is not a macro lens. The close-focus point is at 39cm from the film/sensor plane, and Canon quotes a maximum reproduction ratio of 0.18x for the lens when set to 70mm. The following example illustrates how close you can get to the subject.
The Canon RF 28-70mm f/2 L USM produces fairly nice sunstars when stopped-down to f/16 or f/22, although be careful to watch out for flare effects when shooting directly into the sun.
Bokeh is a word used for the out-of-focus areas of a photograph, and is usually described in qualitative terms, such as smooth / creamy / harsh etc. Canon have employed an iris diaphragm with nine rounded blades for a pleasing rendering of the out-of-focus highlights. Based on what we have seen, we can say that they have largely succeeded. Below you'll find some examples, but you are also encouraged to check out our sample images.
In order to show you how sharp the Canon RF 28-70mm f/2 L USM lens is, we are providing 100% crops on the following pages.