Conclusion

With a price-tag of just £319 / $299, the Canon RF 16mm F2.8 STM is a very cheap and very cheerful ultra-wide-angle prime lens that delivers sharp images in the centre, fast and reliable auto-focusing, usefully close shooting distance, and surprisingly good build quality, all housed inside a tiny, super-lightweight design.

It delivers excellent sharpness at the centre of the frame throughout most of its aperture range, even performing very well when shooting wide-open at f/2.8. It's a different story at the edges of the image, though, which are much softer, with best results obtained from f/5.6-11.

When shooting JPEGs and video, there's some fairly mild vignetting which requires you to stop down by at least 2 f-stops to prevent it completely, but there's little evidence of chromatic aberrations. Distortion is also well controlled as the camera body automatically applies corrections to the image.

Shooting in the RAW format, however, is another matter entirely, because the lens relies so heavily on Canon's digital corrections which are either applied automatically in-camera or by the end user during post-processing.

These corrections aren't automatically applied to RAW files, which clearly exhibit huge amounts of barrel distortion and vignetting that some users may find objectionable.

Currently you'll have to use Canon's Digital Photo Professional 4 software to post-process the Raw files and make them usable, at least until Adobe, Capture One et al release their own profiles for this lens.

This is by far the biggest compromise in producing such a small, light and cheap wide-angle lens - there really isn't too much else to complain about given the asking price.

The fly-by-wire manual focusing isn't particularly refined and it's also rather noisy in operation, there's no weather-proofing, and you don't get a case or even a hood included in the box, but we think they're pretty minor gripes for what is after all only a £$300 lens.

Overall, if you can buy into the amount of digital correction that Canon is automatically applying to in-camera JPEGs, or wants you to apply in post to Raw files, then we can highly recommend the RF 16mm F2.8 STM for your ultra-wide-angle and vlogging needs.

Ratings (out of 5)
Design	4.5
Features	4
Ease-of-use	4.5
Image quality	4
Value for money	5