Pentax SMC DA* 60-250mm f/4 ED [IF] SDM
¡Excellent!. It is very sharp (center and edge) (very good to ex. resoliution), vignetting and lateral CAs are well controlled. Photo print in DIN A4 and 800 ISO, perfect. No noise. F4 is enough. The weight is important 1 Kg. (simitar zoom SIGMA or TAMRON f 2,8 ( 1,3 kg)). You can see the tecnical review in "photozone". The build quality is exceptionally high and up to pro standards. The AF not blazingly speedy.