Canon RF 28mm F2.8 STM Review
Introduction
The Canon RF 28mm F2.8 STM is a super-compact wide-angle pancake prime lens for Canon RF-mount 35mm full-frame mirrorless cameras that won't break the bank.
This is an extremely compact and lightweight lens, yet it still offers a bright maximum aperture of F2.8 for better low-light performance and bokeh effects.
It features 8 elements in 7 groups including three aspherical PMo elements to help control distortion and a Super Spectra Coating to help reduce flare and ghosting, plus a 7 blade diaphragm which creates an attractive blur to the out-of-focus areas of the image.
An internal focusing mechanism means the lens barrel doesn't move, and it offers a minimum focusing distance of 23cm / 9.1" and a maximum magnification ratio of 0.17x, whilst using cost effective 55mm filters.
Perfect for travel photography, street and everyday life, the Canon RF 28mm F2.8 STM lens is available now priced at £325 / $299 in the UK and the US, respectively.
Ease of Use
Weighing in at 120g / 4.2oz and measuring nearly 7cm / 2.7" in length, the RF 28mm F2.8 STM is a super-lightweight, tiny wide-angle prime lens.
It's barely noticeable when used with a mid-sized camera body like the Canon EOS R8 body that we tested it with, as shown in the product photos.
Build quality is good for such an affordable lens. Despite its mostly plastic construction, the RF 28mm F2.8 STM feels solid in your hand, and it commendably has a metal mount.
Note that this lens does not have a weather-resistant design to help protect it against dust and moisture.
There's also no optical image stabilizer built-in to this lens, though arguably you don't really need this feature on such a small and light wide-angle optic.
If you're not using the focusing ring for manual focusing, you can change its operation to be the Lens Control Ring instead via the dedicated Focus/Control switch on the side of the lens barrel.
In this Control setting, the ring can be used to control certain key camera settings (TV, AV, ISO and exposure settings) instead of the focusing.
The Canon RF 28mm F2.8 STM lens has a very narrow fly-by-wire focus ring with a ridged grip band.
There are no hard stops at either ends of the range, making it more difficult to set focus at infinity.
Note that this lens usefully offers full-time manual focusing even when AF is selected.
In use the manual focusing system emits an audible "whining" noise that makes it less suitable for video than stills.
Polariser users should be pleased that the sensible 55mm filter thread doesn't rotate on focus.
When it comes to auto-focusing, the RF 28mm F2.8 STM is a snappy performer thanks to the STM motor, taking around 0.10 seconds to lock onto the subject when mounted on the Canon EOS R8 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, thanks to the superb low-light capabilities of the EOS R cameras.
The STM motor is also pretty quiet in AF mode, emitting a much quieter "whirr" than when manually focusing, which makes this lens well-suited to auto-focusing during video recording.
There is a petal shaped lens hood (EW-55) and a soft case (LP811) available for this lens, but disappointingly both are optional extras that aren't included in the box.
Focal Range
The Canon RF 28mm F2.8 STM's focal length of 28mm provides an angle of view of 75°.
Chromatic Aberrations
Chromatic aberrations, typically seen as blue or purple fringes along contrasty edges, were not especially apparent in our test shots, only appearing in very high contrast areas.
Vignetting
When shooting JPEGs, with the lens set to its maximum aperture of f/2.8, there is some obvious light fall-off in the corners, requiring you to stop down by at least 2 f-stops to prevent it.
There's a large amount of vignetting evident in the RAW files, though, but thankfully the Canon EOS R8 camera automatically and successfully applies corrections to the JPEG files, resulting in an acceptable out-of-camera image.
JPEG
RAW
Distortion
You cannot actually turn off distortion correction in an EOS R camera body when this lens is used - the menu option is actually greyed out and unavailable - which perhaps gives you a good idea of just how much correction the camera is applying!
Still, distortion is well controlled in the resulting images, so arguably the combination of camera and lens are doing a good job.
JPEG
RAW
Sunstars and Flare
The Canon RF 28mm F2.8 STM is capable of creating some very nice sunstars when stopped-down to f/22, as shown below, and flare is also well controlled even when shooting directly into the sun.
Macro
The Canon RF 28mm F2.8 STM offers a very useful minimum focusing distance of just 23cm / 9.1", with a maximum magnification of 0.17x.
Bokeh
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.
In the RF 28mm F2.8 STM lens, Canon have employed an iris diaphragm with 7 rounded blades, which has resulted in quite nice bokeh in our view for such a wide-angle lens.
We do realise, however, that bokeh evaluation is subjective, so we've included lots of examples below for your perusal.
Sharpness
In order to show you how sharp the Canon RF 28mm F2.8 STM lens is, we are providing 100% crops on the following page.