The Sigma APO EX DC HSM II 50-150mm is one of the most difficult lenses to find right now in the Sony mount. This is because Sigma discontinued it in February 2011 and announced its replacement, the new optically stabilized version. The new version not only negates one of the big selling points of the earlier model (which I will get to in a moment), it also cannot be purchased anywhere yet. So for those who wanted a nice compact lens that gives a similar (actually longer) focal range than a 70-200/2.8 on a fullframe camera good luck finding this lens, but if you can find it – buy it, and if you have it – don’t sell it.
The 50-150 occupies a focal range that currently has not become popular among other manufacturers. Tokina did produce a 50-135/2.8 but it was never offered in the Sony mount. The 50-150 is designed to give APSC format cameras the same focal range that a 70-200 lens gives on a fullframe camera. In my opinion, this is something manufacturers need to continue expanding on, offering more fullframe equivalent focal ranges for popular lenses. The crop factor can be handy at times when you need that extra bit of reach, but at other times you need that original focus range and working distances that a 70-200 was intended to give you. I know many a time while shooting with the Tamron 70-200 I’ve needed to take a few steps back but if I’d had the Sigma 50-150 it would have been perfect for what I was trying to do.
So, what was the other big selling point I mentioned before? The size of the lens, the 50-150 is incredibly compact. It is about the same size as your average 70-300 kit zoom lens, or the Minolta 70-210 beercan. Optically the lens is nearly as good as you should expect – its plenty sharp at 2.8 and most focal lengths and it gives really nice subject isolation at 2.8 with a very acceptable bouquet. For more information on the performance characteristics on this lens, I highly recommend reading the Photozone.de review (see links below). Here is a comparison showing the size of the 50-150 to the beercan (left) and the Tamron 70-200 (right):
The new optically stabilized version of this lens is much larger, in fact it is over 2 inches longer making it almost as big as your average 70-200 f/2.8 lens. This makes the new version of the lens far less useful, and all it adds it optical stabilization – which in many cases is great to have, but for that much of an increase in size it is not worth it. Not to mention the fact that OS is useless for Sony users since the camera has built in stabilization. So that is my appeal to Sigma – please reconsider offering the non-OS version of this lens because the compact size is one thing that makes this lens really great.