My 55-300 is softer at the long end in portrait orientation - no way to get it sharp there at 300mm. In landscape it's better. I have had problems with my 60-250, as it wasn't sharp. But I sent it in for repair. I think I'll let a picture do the talking. This is a crop from the far right of the frame (very near to the edge) at 250mm and f/4, shot with a K-3:
Yeah it's not a great picture. But in terms of sharpness, it's excellent. A crop from the left side is a little softer but nothing major. In the center it's even better than this, let alone going to f/5.6. The 55-300 is good, but it's not this good.
Last edited by starbase218; 05-15-2015 at 06:17 PM.