I'm not an outspoken fan of this lens as much as @pepperberryfarm is, but recently I found that the Porst/Cosina MC f/1.2 55mm in PK mount is quite better than I believed. It has its pluses (and of course its minuses) vs. the Pentax 1.2/50mm and Revuenon/Tomioka 1.2/55mm.
I found that being funkier wide open than the others, it needs plenty of accuracy in nailing the right focus.
I fitted the O-ME53 to my K-1, and I'm leaving it on even when I'm not using fast manual lenses. Unfortunately it's not enough.
Enlarged LiveView is a must with this lens, cause the rendering wide open makes manual focus through the viewfinder very tricky.
I had glued a bit of aluminum foil to the bayonet to allow for green button functionality (if it doesn't shorten the proper pin the camera thinks there is a T-mount with no lever to close immediately before it takes the picture). The foil came off after a while, so I bought adhesive copper tape on eBay, cut a small square, and taped it at the right place.
With this simple trick the lens can work stopped down, which means that it can come handy in all those situation when shooting wide open is better avoided.
On the second night of Loi Krathong festival I took out the lens to shoot some night pictures.
Unfortunately there is no intermediate click between f/1.2 and f/2, so I decided to shoot at f/2.
It is more than one stop difference, so the rendering of the optic gets far less extreme.
If you nail the focus, like in the following image, the sharpness is quite good and there still is plenty of "character".
Porst Color Reflex MC f/1.2 55mm @f/2
Last edited by cyberjunkie; 11-23-2018 at 03:02 AM.