Yongnuo 35mm f2: Yongno or Yongyes?
The Yongnuo 35mm f2 lens retails new for around $100 and sells used for $20-30 less. This lens is roughly 1/4th the cost of the Nikon 35mm f2 AF-D, but the Nikon has much better image quality. (Alternatively, if you are using the DX format, you may want to look into the Nikon 35mm 1.8G DX lens that sells for around $200.) While the build quality on this Yongnuo is actually quite nice, it suffers from a cheap lens cap (a minor issue) and a questionable focus ring. The cap is never easy to fully install, and the focus ring, while well-damped, feels like it might break if you push it too far or fast. At least the lens cap is an easy replacement. Moving on, bokeh is decent, if not distracting. Disappointingly, the main faults of this lens are that it isn’t super sharp or contrasty. This lens is fine for most purposes, but it is not for those who demand excellent image quality. The saving grace of this lens is its auto-focus, which is a dream to use, being near-silent and incredibly agile.
To conclude, the Yongnuo 35mm f2 is a high-value, lightweight lens with decent build quality and excellent auto-focus, but more discerning users might be disappointed with the sharpness and contrast. Crop sensor camera users should probably skip this and check out the Nikon 35mm 1.8G DX, which brings much better quality and a slightly increased maximum aperture for around $100 more. Full frame users should consider the four-times as expensive Nikon 35mm f2 AF-D but not without considering this budget Yongnuo first.
These photos were taken with this lens on a D600 (for the dogs) and a Df (for the tree). At these sizes, the image quality issues are not really relevant.