Yongnuo YN 50mm F1.8 DF DSM II

The Yongnuo YN 50mm F1.8 DF DSM II is a compact full-frame 50 mm prime that Yongnuo sells for Sony E, Nikon Z and, as a "Multi-mount" lens, for Canon RF bodies. The shop calls the E and Z versions the "Lite Version" and the "II" successor to its earlier heavier 50 mm F1.8 DF lenses. The Canon version (model 50F1.8R DF) has the same optical specification.

Optical design

Yongnuo specifies 10 elements in 6 groups, an aperture range of f/1.8 to f/16 and nine circular aperture blades, which give 18-point star effects when stopped down. The glass includes one extra-low-dispersion and one low-dispersion element, with a nano-multilayer coating against ghosting and flare and a fluorine coating on the front element. The angle of view is 47.4 degrees diagonal, 39.5 degrees horizontal and 26.5 degrees vertical.

Autofocus and handling

A digital stepping motor (DSM) drives the focus, which Yongnuo describes as fast, quiet and suitable for video. The minimum focus distance is 45 cm at 0.13x magnification. The shop lists customizable Fn buttons and a control ring for the E and Z versions, and an AF/MF switch. For removing the Canon RF version, Yongnuo notes that the unlock button on the lens must be pressed and held. A USB-C port allows firmware updates.

Build and size

The lens has a metal bayonet with gold-plated contacts, a rubber gasket at the mount and an anodized aluminium focus ring. The filter thread is 58 mm. The maximum dimensions are about 68 x 79 mm for Sony E, 68 x 80 mm for Nikon Z and 68 x 77 mm for Canon RF. The weights are about 273 g (E), 282 g (Z) and 276 g (RF) without caps. White versions are available for E and Z.

Where it fits

The database lists many 50 mm options: the Sony FE 50mm F1.8, the Canon RF 50mm F1.8 STM, the Nikon Nikkor Z 50mm F1.8 S and the 7Artisans AF 50mm F1.8 for E and Z. Yongnuo's version sits in the budget corner, with a nine-blade aperture and a 273 to 282 g weight.

Pros and cons

Pros

• Full-frame coverage and f/1.8 in a lens under 300 g
• Nine aperture blades
• Same 58 mm filter size on all versions
• USB-C firmware updates

Cons

• 45 cm minimum focus distance
• No optical stabilization
• No Fn button or control ring is listed for the RF version
• The Canon version is not marketed as a Canon RF lens

Verdict

The YN 50mm F1.8 DF DSM II is a light, simple full-frame standard lens for three mirrorless systems. It fits users who want a basic bright 50 mm with autofocus and a small footprint and who do not need weather sealing or stabilization.