Might be similar - I bought a Sigma 400mm lens (a few years ago) for fairly cheap. I found that the lens (optics) were more than acceptable - impressive, I might say (even though the lens was a painfully slow 5.6 - but I harly ever shoot ANY lens wide open anyway.) The problem came about six months later - when the cheap lens collar (made of a lightweight plastic) simply gave out (cracked completely in half) - so this otherwise decent lens has been sitting in a drawer for the past eight years. For the most part, the manufacturing of lenses today is so computer CNC controlled that excellent optics are fairly easy to achieve - but the "wrapper" that the lens is presented in can make all the difference in the world. Perfect optics in a plastic case that tends to swell and shrink with the slightest temperature change (especially with a long lens), will drastically alter the performance of the lens. there's no replacing a "solid-feeling" lens. I have no experience with the lens you're asking about - it may be a wonderful lens (but $200? - i would have to be cautious) if at all possible, get ahold of one and test shoot it in several environments, and then judge for yourself. Just my $3.89 worth (I've decided to charge a bit more!) Wolf