In summary
Compact, lightweight and affordably-priced, the RF 16mm f/2.8 STM lens would be a worthwhile investment for anyone who needs an ultra-wide prime lens that is compact and easy to carry.
Performance-wise, it will be equally suitable for professional and enthusiast photographers, although we’d recommend budgeting for an EW-65C lens hood to accompany it.
Full review
Announced in mid-September 2021, Canon’s RF 16mm f/2.8 STM is similar in design to the RF 50mm f/1.8 STM lens and covers the widest angle of view in the company’s mirrorless prime lens range. There’s only one lens with wider coverage, and that’s the RF 14-35mm f/4L IS USM lens, which is considerably larger and more complex. Like its 50mm sibling, the 16mm lens is small and light enough to pair with the entry-level EOS RP camera, which allows it to be used with gimbals or even mounted on a drone. We reviewed this lens on an EOS R6 body.
Angled view of the RF 16mm f/2.8 STM lens. (Source: Canon.)
The optical design of this lens (shown below) is relatively simple with nine elements (one of them aspherical) arranged in seven groups. Canon’s Super Spectra Coating has been applied to minimise ghosting and flare. A rounded seven-blade diaphragm produces a pleasing bokeh quality.
This diagram shows the position of the aspherical element in the optical design of the RF 16mm f/2.8 STM lens. (Source: Canon.)
Like the RF 50mm f/1.8, the RF 16mm f/2.8 STM lens is neither weather-resistant nor stabilised. It also uses a stepping motor focusing drive, which is fast and operates smoothly but is not guaranteed to be totally silent. The front-focusing design extends the inner barrel as the focus distance decreases to a minimum focus of only 13 centimetres.
The lens is supplied with front and rear caps but the compatible EW-65C lens hood is an optional add-on. Expect to pay approximately AU$45 for it, regardless of where you shop.
Who’s it For?
The affordable price tag will probably attract keen photo enthusiasts to this lens – especially if they also want a lens that can be easily slipped into a pocket where it will be ready for use when needed. Its very wide (a little more than 108 degree) angle of view will attract landscape photographers as well as those involved in real estate as well as architectural and interior photography.
Astro-photography is another type of photography for which this lens is well suited, particularly for photographing the night sky. Wedding and event photographers could find this lens handy for taking ‘environmental’ shots of people in venues, such as the bride and groom coming down the aisle or the start and finish of a race.
Mounted on a drone, it could be used to capture a bird’s eye view of sports arenas, localities or landscapes when shooting videos as well as stills. On a gimbal or extending arm it could be used to photograph the cockpits of aircraft or vehicle interiors.
At a pinch, it could also be fitted to a remote sports event camera for snagging close-up action shots – although it’s not weatherproof so care will be needed in deciding how to set it up. Used as a vlogging camera with the EOS Webcam Utility software, it will allow creators to integrate environments into their productions, whether they work indoors or out.
Build and Ergonomics
Canon doesn’t list the materials used in the construction of this lens but, like the 50mm lens it is probably made mostly of polycarbonate plastic with a solid metal mount that connects to the camera. Build quality is good for a mostly plastic lens, although this lens is not weather-sealed.
There’s only one ring, the programmable control ring found on all RF lenses which, in this lens can be manual focus adjustment but can also be programmed to adjust aperture, ISO or exposure compensation. Located just behind the front of the outer barrel, it is 9 mm wide and textured to make it easily identifiable by touch. A slider in the 25 mm wide section of the lens barrel behind the control ring is used to switch between focus and control modes.
A 3 mm wide strip of gunmetal grey separates the body of the lens from the metal lens mount, which has the usual 12 contact points around its inner edge for passing electronic signals between the lens and the camera. The diameter of the front element is 22 mm and the lens accepts 43 mm diameter filters.
Performance
Our Imatest tests showed the review lens to be capable of exceeding expectations for the 20-megapixel sensor in the EOS R6 camera – although only in the centre of the frame. Resolution fell below expectation roughly half way out from the centre and declined even further towards the periphery. This pattern was true for both JPEG and CR3.RAW files, although the latter were generally higher in resolution.
The highest resolution occurred at f/4, with a slow decline to f/8 where diffraction began to take effect. Interestingly, central resolution remained much higher than peripheral resolution from about f/3.5 onwards, as shown in the graph of our test result below.
The EOS R6 automatically corrects chromatic aberration in JPEGs so the graph of the results of our tests below shows lateral chromatic aberration well down in the ‘negligible’ band the upper edge of which is defined by the red line. However, uncorrected CR3.RAW files contained a high degree of coloured fringing towards the edges and corners of image frames, as shown in the samples at the end of this review.
Both vignetting and rectilinear distortion are expected in such wide angle lenses, although they are normally removed by the in-camera corrections applied to JPEGs. Analysis of uncorrected raw files showed the review lens was affected by strong vignetting in the form of edge darkening at wide aperture settings, although most of the effect had vanished when the lens was stopped down to f/4.5.
Barrel distortion was also obvious in uncorrected files. Interestingly, while in-camera distortion correction effectively cropped away the distorted areas, it also tended to increase the effects of edge softening since it involved stretching the image.
Autofocusing was as fast and accurate as you’d expect from a wide angle lens and also virtually noise-free. There was also no evidence of focus shifting as the lens was stopped down.
Backlit subjects were handled very well for such a wide angle lens. We found few instances of flare artefacts and no signs of veiling flare, including in shots with a bright light source within the image frame. Despite its ultra-wide angle of view, the lens could also produce nice, 14-pointed sunstars at bright highlights when stopped down to f/22.
Bokeh quality is seldom seen as an essential feature in wide angle lenses and it should be no surprise to learn the RF 16mm f/2.8 STM lens does not produce soft, round defocused highlights. Instead, highlights tend to become elongated towards the edges of the frame and outlining is relatively common.
Nonetheless, the short close focusing distance of this lens can make it useful for some close-up work, especially when defocused backgrounds are not needed. Some examples can be found in the samples section at the end of this review.
Conclusion
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SPECS
Picture angle: 108 degrees 10 minutes
Minimum aperture: f/22
Lens construction: 9 elements in 7 groups (including 1 aspherical element), Super Spectra Coating
Lens mounts: Canon RF
Diaphragm Blades: 7 (rounded aperture)
Weather resistance: No
Focus drive: Stepping motor (STM)
Stabilisation: No
Minimum focus: 13 cm
Maximum magnification: 0.26x
Filter size: 43 mm
Dimensions (Diameter x L): 69.2 x 40.2 mm (when inner barrel is retracted)
Weight: 165 grams
Standard Accessories: Front and end caps
Distributor: Canon Australia; 1800 021 167
TESTS
Based on JPEG files taken with the EOS R6 camera.
Based on CR3.RAW files recorded simultaneously and converted into 16-bit TIFF format with Adobe Camera Raw.
SAMPLES
Vignetting at f/2.8.
Rectilinear distortion.
ISO 200, 1/200 second at f/11.
Crop from the above image at 100% magnification showing purple fringing.
Close-up at f2.8; 1/1000 second, ISO 200.
Two crops from the above image at 100% magnification showing highlight outlining and non-circular bokeh.
Close-up at f3.5; 1/640 second, ISO 200.
Crop from the above image at 100% magnification.
Minimum focus distance at f/11; ISO 200, 1/320 second.
Close-up at ISO 200, 1/160 second at f/9.
JPEG image with in-camera corrections applied; ISO 200, 1/80 second at f/8.
This sample is taken from a simultaneous CR3.RAW file without distortion corrections; ISO 200, 1/80 second at f/8.
JPEG image with in-camera corrections applied; ISO 800, 1/60 second at f/14.
Taken from the CR3.RAW file recorded simultaneously with the above JPEG image without distortion corrections applied.
Sunstar at f/22; ISO 100, 1/8 second at f/22.
Angular distortion produced by tilting the camera; JPEG file with corrections applied; ISO 200, 1/320 second at f/9.
Backlit scene; ISO 200, 1/320 second at f/10.
ISO 200, 1/640 second at f/11.
ISO 200, 1/160 second at f/13.
ISO 200, 1/500 second at f/9.
ISO 200, 1/640 second at f/11.
ISO 250, 1/60 second at f/10.
Rating
RRP: AU$499; US$299.99
- Build: 8.8
- Handling: 8.8
- Image quality: 9.0
- Autofocusing: 9.0
- Versatility: 8.5
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