There are three versions of this... 1) oldest - 28-70/2.6-2.8, very good build quality, optically presumably great
2) AT-X "SV" - cheaper version 28-70/2.8 , less good build quality (more plastic, not so smooth zooming et cetera, I would rate it analogous with 19-35/3.5-4.5 or similar), goes new for about 300Euro) 3) AT-X PRO 28-80/2.8, pro series, the best now. Costs about 2-2.5x more than the SV version!!! I didn't exactly like the SV version. There was significant veiling at full aperture, although similar to same price lenses from Sigma. Guess if you want high quality you have to pay for it. For casual use, I would say it's pretty good though. Good light! fra