| I was just looking for a reply like this - 24x36NOW has hit the nail on the head. The further away you go from a zoom ratio of 1:3, image quality degrades, be it any brand, any range, any number of glass elements. The 28 from 28-300 is not as good as 28 from 28-80, and same goes to the tele end also - a 200 from 28-200 is not as good (read sharp / contrasty / whatever) as 200 from, say 70-210. I guess it is the complexity of optical design which gives this general 1:3 ratio as the upper limit of acceptable quality.
The wider aperture will also play its role in improving the image quality, which is another plus. But that is anyways the case. |