I have had a Sigma 70-300 APO macro for about 15 or 16 years. It was originally used on a Minolta 600si but is now on my Sony A350 where it is a massive 450mm telephoto (35mm film equivalent) Sure it wasn't expensive but is an excellent lens for its price, better than the Sony kit lenses which are somewhat soft. You can spend thousands on a lens, not everyone can afford that. I am very satisfied with the Sigma