A fast wide angle with good performance and a very pretty design. In fact that might be an understatement. The lens is outright beautiful. The phrase "they don't make them like they used to" really comes to mind here. On top of that it's a pretty OK lens though it is a bit soft at f/2.8. The lens is also very large and heavy for an M42 lens with a comparatively huge 62mm filter thread. The Yashinon-DX line were designed by Tomioka Optical Works in the late 60's and are highly sought after. I managed to find mine at the local PhotoFair for a reasonable-ish price. Being honest if you're after a good optic at an affordable price many other lenses are better deals but if you can get a good price or are just interested in its looks than go for it.
Mount: M42 Screw Mount
Focal Length: 28mm
Aperture Range: f/2.8 - f/16
Minimum Focus: 0.4m
Filter Thread: 62mm
Date Acquired: 05/18/19
Serial Number: 2882431
Purchase Price: $100
Going Price: ~$250
Condition: Slight wear but otherwise pristine
Like all the Yashinon-DX lenses this one is built like a Swiss watch - simply beautiful. The lens is gorgeous to look at and is as mechanically fine as it looks. The focus is smooth and the aperture functions well. There is an automatic/manual switch to toggle if the aperture pin needs to be depressed in order to function. The only real complaints I have are how the aperture is hidden in a small cutout window and the lens is unusually large for a vintage 28mm. This makes the lens a little more ungainly than it should be but these flaws are also shared across the entire Yashinon-DX line.
Unfortunately unlike the Yashinon-DX 50mm f/1.4 which is a stellar performer the 28mm isn't so great. The center is a little soft wide open but sharpens nicely by f/4. The corners however never really improve only becoming acceptable by f/11. Vignetting is dramatic and also still present even at f/11. This is even more disappointing given the huge 62mm filter thread hiding a large front element. The lens bokeh is mostly smooth but point sources are rendered as distinct "bubbles" that deform toward the edges of the frame. This can be an interesting effect or incredibly distracting depending on the subject. The 6 straight aperture blades cause those point sources to become hexagons as you stop down. Lens flare is intense as you can see flare even in the resolution test images.
The lens is a pleasure to use. The focus is smooth and the aperture ring is easily accessible. It is on the large size but in practice this isn't a problem. The only real limiting factor is the knowledge that the f/2.8 aperture isn't really usable. You end up shooting at f/4 negating the advantage of the lens's faster speed than the more common f/3.5 28mm lenses.