CoC (Circle of Confusion) vs sharpness from the manual focus TTArtisan 50mm F1,2 lens at full lensopening.
This altered Sonnar design (6 + 1 = 7 lens elements), although from the same lens familie of double gauss designed lenses, delivers a less nervous bokeh (is more pleasing, less distracting in relation to the main subject) to my opinion, then the Biotar or Biometar lenses and their copy's.
This lens center sharpness is already good at full lens opening, very good at F1,4 and excellent from F2,0 upward.
When doing so the diameter of the CoC will get smaller, while gaining overall sharpness.
For the most pleasing effect use this lens between F1,2 and F2,0 to your likings, i prefer F1,2 and F1,4, from F2,0 upwards when outstanding sharpnessis requiredi i prefer the Leitz Summicron 50mm F2,0 lens.
But in relation to the price point of 98,- dollar, it gets excellent status from me and also in the Jonas Rask and in the Sony Alpha Blog review. (see below).
A second hand Summicron 50mm F2 will cost 5 till 20 times more the the 50MM F1,2 TTArtisan, and with the 50MM F1,2 TTArtisan you will have the bonus that it can be used on F1,2 and F1,4 as well with excellent results.