Originally posted by Docrwm Vivitar 19mm f3.8 Wide Angle MC ]
This lens is unjustly underappreciated.
You got to stop it down, then the result is quite good, and works a treat with P-TTL and any camera mode (not many PKA lenses in this focal range).
Really it's a 20mm more than a 19mm (the Cosina version was sold as a 20mm). I don't find it too disturbing. I am more concerned by the performance, which has proved to be satisfying. I took test shots in PixelShift mode and I saw a definite increase in sharpness, which means that the optic works well enough at medium apertures.
This lens could well give the best price/performance ratio of all the 20mm's that can be used on a Pentax camera.
Of course the Pentax-A 2.8/20mm is better, but it is also way more expensive...