Best mid-price telephoto lenses

How much should you pay?A telephoto zoom is the first additional lens most DSLR or compact system camera owners go for. These can be pretty cheap but, unfortunately, the performance can be disappointing.Cheap telephoto zooms tend to lose sharpness at their maximum zoom setting, which is where you most often want to use them.Cheap telephotos also have a maximum aperture that shrinks as you increase the zoom. They might start out at f/4, for example, at their shortest zoom setting, but as you zoo