The 18-250mm f/3.5-6.3 DC Macro OS HSM is the latest in a long line of all-in-one 'superzoom' lenses from Sigma, having been announced in June 2012. It offers two main developments over its predecessor, the confusingly similarly-named 18-250mm f/3.5-6.3 DC OS HSM - namely improved close-up capability (hence the 'Macro' moniker), and a significant reduction in size and weight. Sigma says the latter is due to the use of a 'Thermally Stable Composite' (TSC) material in the construction of the lens barrel, which makes it almost identical in size to its main rival - the Tamron 18-270mm F/3.5-6.3 Di II VC PZD.
Like Tamron, Sigma has included optical image stabilization in the lens design, promising the ability to hand-hold the lens at shutter speeds four stops slower than usual before camera shake becomes a problem. The lens features an ultrasonic-type 'Hypersonic Motor' for quiet focusing, which means it will autofocus on entry-level Nikon SLR bodies. Despite its improved close-focusing abilities, the optical formula is actually a bit simpler than its predecessor's, and uses only a single Super-Low Dispersion glass element rather than four. Three aspheric elements are also used in the 16 element, 13 group design.
The 18-250mm offers an impressive wideangle to telephoto range (equivalent to roughly 28-400mm on full frame), which is beaten only by the aforementioned Tamron 18-270mm F/3.5-6.3 Di II VC PZD and the recently-released Nikon AF-S DX Nikkor 18-300mm F3.5-5.6G ED VR. It will be available in Sigma, Nikon, Canon, Sony and Pentax mounts, although the latter two versions won't feature optical stabilization and will rely on the cameras' built-in systems instead. As usual for a new product it comes to market at a higher street price compared to its predecessor, but look a little closer and the RRP has actually dropped.
- Approx. 28-400mm equivalent focal length range; F3.5-6.3 maximum aperture
- Available for Canon, Nikon, Pentax, Sigma and Sony mounts (APS-C/DX format DSLRs only)
- In-lens Optical Stabilization system (excluding Pentax and Sony versions).
- Hypersonic Motor (HSM) focusing
- 0.35m closest focus (0.34x magnification)