Originally posted by pres589 Sigma 30's might be cool but too many AF horror stories for me to want to spend my money for one.
My Sigma 30mm non-Art is the best lens for night photography I've ever used (for crop format).
At least on my K-5 II it never gave AF problems. Now I'm mainly using a K-1, so the lens is sort of retired. I miss it, though.
The only problem/feature is field curvature, it's never sharp at the borders like at the center of the picture.
For full frame, I own most of the lenses that have been mentioned.
The Samyang 24mm is great, but also quite big, and too wide to be an ideal walk around lens (IMHO).
The Kiron/Vivitar 2/28mm is a good choice for MF. The Sigma Mini-Wide II 28mm is a good OPTION too, if you don't need f/2, and is also available in AF version.
I just found a nice example (M42 mount) of the Soligor C/D 'P' 2/28mm, made by Tokina. Same family of the famous 2/135mm I love (and use very often). I'll see how it fares. It should give a nice out of focus rendition, that's the reason I've been looking for that lens for a while..
If 35mm is wide enough, Makina Japan made a 1.8/35mm sold under various names, that is quite good for bokeh-oriented photography