Pay careful attention to the following product name: Sigma 18-250mm f3.5-6.3 DC Macro OS HSM. See that “Macro” in there? Good, because outwardly, that’s the only indiciation that this 18-250mm is different from the existing one in Sigma’s line-up. So, why the new lens? Two reasons. One, the lens now has much improved macro capabilities, up to a maximum ratio of 1:2.9 from 1:3.4. The other reason? The lens uses Sigma’s new Thermally Stable Composite (TSC), which acts as a replacement for polycarobonate, except is thinner and expands and contracts notably less with temperature changes. This allowed Sigma to shave .2″ off the diameter, .5″ off the length, and drop 6 ounces of weight. None too shabby.
Availability is slated for July, and no pricing is available yet.