Normally we'd be suspicious of optics costing so little, but in the past Yongnuo has proven itself to deliver great quality products at low prices. Like other lenses of its type, the YN50mm f/1.8 II is compact and lightweight. While the barrel has a plasticky (yet solid) feel, the mount itself is metal, which is unusual on budget lenses. The barrel has a minimalist black design, with a red line running along the front rim, just below the thin manual focus ring, and sports a focusing scale in feet and metres. On the left side is a switch to change between AF and manual focus.
The lens boasts a fast maximum aperture of f/1.8 and a minimum aperture of f/22. It sports seven blades in its iris, which Yongnuo claims gives 'super bokeh' when used at wider f/stops. A minimum focus of 35cm and reproduction ratio around one-fifth life-size is par for the course for this type of lens, so it's fine for still-lifes but not for close-ups. The 58mm filter thread is one of the larger diameters of current 50mm f/1.8 lenses and it's the same as the 18-55mm kit zoom, so any filters/filter rings users have for that can be used with this lens too. The front section of the lens doesn't rotate during AF, which is a benefit if you use a polariser or an ND grad.
The Yongnuo's AF system lacks a USM or STM as found on Canon lenses, so while it's not as quiet, its autofocus is still fast and responsive, even managing to track slow-moving subjects, albeit in a staggered fashion. Its performance is more than adequate for capturing images, but Canon's 50mm STM is far better for video. The lens lacks electronic focusing, so when you want to use manual focus you need to switch the lens from AF to M to avoid damaging the motor. The thin focusing ring might annoy some but I found it more than adequate to use and the light action makes focus adjustments fast and easy.
So handling and AF performance score well, but how does the Yongnuo fare in terms of its optics? You'll be glad to know it's great, providing similar sharpness to the Canon equivalent at most apertures. It's a little softer at f/1.8 but even wide open sharpness is good, while stopping it down to f/2.5 sees a big improvement, with f/8-11 giving the sharpest results. There is a little light fall-off towards the edges but nothing to be concerned with, but do take care outdoors as flare can be a problem. Overall, it's a true budget alternative to the Canon.
At around £50, the Yongnuo YN50mm f/1.8 is one of the most affordable optics available. Yet it delivers a performance that stands up against more costly models. While images at f/1.8 aren't super-sharp, pretty much everything else it delivers is better than its price might imply.
Guide Price: £53
Lens construction: Six elements in five groups
Number of diaphragm blades: Seven
Minimum aperture: f/22
Minimum focusing distance: 35cm
Maximum magnification: 0.21x
Filter Size: 58mm
AF Fittings: Canon
Supplied accessories: Front & rear lens caps