The Pentax-A 55mm f/2.8 is a manual focus lens made to old-style standards: metal. Build quality and focus “throw” are much better than the new Pentax-D FA 645 55mm F2.8 AL[IF] SDM AW. But optical performance is little better, if at all.
As will be seen performance is reasonably good, but with moderately strong lateral chromatic aberration (red/cyan color fringing).
This is the entire frame as shot (shade).
I used a Zeiss 3X focusing loupe on the viewfinder to focus as well as could be. I shot two series. Both were sharp, so I think this represents what the Pentax-A 55mm f/2.8 can do.
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