Sigma - 18 mm to 250 mm - f/6.3 - Macro Zoom Lens for Pentax K

The addition of the 18-250mm F3.5-6.3 DC Macro OS HSM speaks to Sigma's versatile product lineup with this multipurpose zoom lens that offers Optical Stabilization (OS)* and covers wide angle to telephoto to macro photography. It differs from Sigma's current 18-250mm F3.5-6.3 DC OS HSM lens with its even more compact size, its macro capability with a maximum magnification ratio of 1:2.9 and the use of Thermally Stable Composite (TSC) material currently used only by Sigma.

TSC, which is incorporated into the lens barrel and is often compared to polycarbonate, has a high degree of elasticity and exhibits little variation in its structure in extreme temperature conditions. This means that internal barrel expansion and contraction due to extreme temperature variations is less prevalent. TSC also contributes to the lens' size reduction. The non-macro 18-250mm F3.5-6.3 without TSC weighs 22.2 ounces and is 3.1 by 4 inches in diameter, whereas the new macro lens is 16.6 ounces and 2.9 by 3.5 inches in diameter.

Sigma optimized this lens' power arrangement by incorporating double-sided aspherical lenses and reexamining the design to achieve a more compact filter diameter. The lens has an approximate 13x high zoom ratio with a filter size of 62mm in diameter. Sigma's unique OS system, as well as one Special Low Dispersion (SLD) glass and three aspherical lens glasses, compensate for camera shake and enable correction of color aberration, respectively.

The new 18-250mm F3.5-6.3 DC Macro OS HSM lens is also equipped with Super Multi-Layer Coating to reduce flare and ghosting, a Hyper Sonic Motor (HSM) to ensure fast and quiet auto-focusing, and a rounded, seven-blade diaphragm to create an attractive round blur to the out of focus areas. The lens features a brass-made bayonet mount applied on the surface to reinforce strength for long-term use and enable high accuracy and solidity.