The Canon RF 28-70 mm f/2 L USM is a bright standard zoom for the new mirrorless Canon EOS R and RP camera. The new, spacious mount and short distance from the mount to the sensor of the Canon EOS R and EOS RP make new lens designs possible. The Canon RF 28-70 mm f/2L USM is one of the new RF lenses that benefits from the new mount. Thanks to the high brightness of f/2, the Canon RF 28-70 mm f/2 L USM allows you to make optimal use the autofocus system of the Canon EOS R. The Canon EOS R can focus down to -6 EV. That is very, very little light. To be able to take pictures with so little light, you need an extremely bright lens, and this 28-70 mm is that. With a largest aperture of f/2, there is little difference in brightness between this zoom and most fixed-focal length lenses. This high brightness ensures that you can work with faster shutter speeds and that you get a nicer bokeh than with standard zooms with f/2.8 or f/4 as the largest aperture.
The range of the Canon RF 28-70 mm f/2L USM is not very big for a modern standard zoom. Most standard zooms start at 24 mm or end at 75 mm, such as the new Tamron 28-75 mm f/2.8 for Sony E-mount. The smaller range is the price that you pay for the high brightness. A larger range would have made the lens much bigger, unless Canon made concessions on the image quality. And we can imagine that the latter was not an option. Because what good is a very bright lens if it is not optically great? Of course, it would have been even better if this zoom had started at 24 mm, but 28 to 70 mm is also a nice range for a standard zoom. The zoom offers a true wide-angle position on the one hand and a light telephoto on the other. Fortunately, you do not miss that extra four millimeters for documentary work. The difference between shots at one extreme or the other is quite substantial:
BUILD AND AUTOFOCUS
To be able to let as much light through a zoom as the Canon 28-70mm f/2 L USM, a big front lens is needed, and that also translates to the filter size. That’s no less than 95 mm. The dimensions and weight are substantial, but for a lens that is this bright, it’s actually not too bad. This is of course an L-lens, which means that the lens is fully sealed against the elements and that dust, dirt and moisture cannot just penetrate. The lens has an MF/AF switch to change between autofocus and manual focusing. The optical design is complex and contains no fewer than four aspherical elements. Just like the other RF lenses, this lens has a programmable ring on the front. That ring is a really nice invention, although it would have been even better if it had been close to the body. That would have improved manageability. All the controls turn very smoothly and solidly. You can feel with your eyes closed that this is an L-lens. The aperture has 9 blades, so that you can get beautiful 18-pointed sun stars at f/11 or f/16 if you shoot against the light. The lens becomes a little bit longer when you zoom out. In fact, the only thing missing on the Canon 28-70 mm f/2 L USM is image stabilization. Whether that is a matter of costs, dimensions, weight or image quality, or all those reasons combined, we will never know. The only thing left is waiting for a Canon EOS body with built-in image stabilization. The maximum magnification is 0.18x. That is a fairly moderate macro setting. The autofocus is fast and quiet, and the lens is almost parfocal. This allows you to zoom without having to keep refocusing, and it’s also ideal when filming with the Canon RF 28-70 mm f/2 L USM.
VIGNETTING, FLARE AND DISTORTION
The vignetting of the Canon RF 28-70 mm f/2 L USM is quite modest. and downright very good if you take into account the extreme brightness. A maximum of 1.2 stops at full aperture in the wide-angle position is very good, and less than one stop at f/2.8 is a value that far less ambitious standard zooms don’t even come close to.
The distortion is also minimal, at least if you use the corrections in the camera. But why wouldn’t you do that? Modern lenses have been designed for that. If you take the trouble to shoot in RAW and use a RAW converter that does not correct, you will see a barrel distortion of 1.5% at 28 mm and 35 mm, an almost distortion-free image at 50 mm and a slight pincushion-shaped distortion at 70 mm. But again, why would you go to all that trouble? You can effortlessly calculate away such a small amount of distortion with an almost imperceptible loss of sharpness. And the files are then almost perfectly free of distortion.
No matter how good and beautiful the Canon RF 28-70 mm f/2 L USM is, we would be very disappointed if this lens had not performed well at full aperture. In the past few years, Canon has actually not released a single L-lens that is not good over the entire range, and this Canon RF 28-70 mm f/2 L USM is no exception. Given the high brightness, that is actually unique. The sharpness is great over the entire range, with a slightly higher sharpness in the center than in the corners, but the gradient to the corners is small and will not really stand out in practice. We see the same thing at every aperture, even at f/2. However, the sharpness increases slightly when you stop down. The lens peaks at f/4 and f/5.6. This lens hardly suffers from chromatic aberrations. At the most, you can see a tiny bit of it at 28mm if you look closely.
The high brightness of f/2 ensures that you can get a beautiful bokeh with the Canon RF 28-70 mm f/2 L USM. This gives you a nice 3D effect in your photos, the difference between your subject and background becomes larger, and you can make busy backgrounds much quieter and less noticeable. With a closed aperture, on the other hand, you can get very beautiful sun stars. For an example of this, see the sample images.
Curious about the performance of the Canon RF 28-70 mm f/2L USM in practice? Click on the button below and visit our renewed web gallery with sample images. The images can be downloaded in full resolution to be viewed at 100%.