Quote:
Originally Posted by glsammy  The biggest difference between the two is the Hyper Sonic Motor the Bigma has. It focuses much faster than the 170-500mm. 
The Bigma is not F4 by the time you get to 170mm. Much the same. If you look around you should be able to get the Bigma for that kind of money. |
so of these x-500mm sigma lenses what which is the 'best' if its possible to say?