Originally posted by clackers Dirty little secret: The 55-300 works fine on the K-1 at the long end!
Actually, it's not quite that simple.
At 55mm there is some soft vignetting (less at infinity focus), but it rapidly increases to be worst at about 100mm.
From 100mm it starts to improve to be negligible at 200mm (especially at infinity)
Vignetting then returns somewhat as you zoom out further. At 300mm it's not bad at infinity, but quite significant at minimum focal distance.
I still consider it a crop lens.
This is with the older HD DA 55-300. The newer PLM version may behave differently.