The Sigma 18-250mm f/3.5-6.3 DC OS HSM was first announced in January 2009, becoming available to buy in March the same year. It's essentially an update to the 18-200mm f/3.5-6.3 DC OS HSM, with an extended 13.9x zoom range bringing it closer in reach to the 18-270mm F3.5-6.3 VC from Sigma's great rivals Tamron. Impressively, the improved telephoto range has been accommodated with scarcely no change in size (Sigma's specifications note a mere 1mm growth in length), and only a modest increase in weight. A notable change though is the addition of Pentax and Sony to the list of supported mounts (alongside Canon, Nikon and Sigma), giving owners of these systems the opportunity to choose between Sigma's in-lens Optical Stabilization (OS) technology and their camera's in-body systems. All versions also use an in-lens HyperSonic Motor (HSM) for focusing; however Pentax owners should note that this won't work on bodies older than the K10D of 2006, which don't support SDM focus motors.

The increase in zoom range has required a substantial revision of the optical formula compared to the older 18-200mm OS. There's the same number of elements (18) which are now arranged in 14 groups, but the number of Super-Low Dispersion (SLD) glass elements has shot up from one to four, and three aspherical elements are also employed to minimize distortion. The minimum focus distance of 0.45m has been maintained, resulting in an improved maximum magnification of 0.29x. According to Sigma, the optical stabilization system now offers up to 4 stops benefit; it also detects when the camera is panning and automatically switches to operating in one axis only, which is useful for shooting moving subjects.

All of these improvements over its predecessor come at a price - the 18-250mm costs some $100/£110 more than the 18-200mm OS at the time of writing, and $220/£180 more than the older, non-OS 18-200mm (which of course gains stabilization on Pentax and Sony bodies). But it's still a bit cheaper than many of its direct competitors, including the Nikon DX 18-200mm F3.5-5.6G AF-S VR II, the Canon EF-S 18-200mm F3.5-5.6 IS, the Tamron 18-270mm F3.5-6.3 Di-II VC, or the Sony DT 18-250mm F3.5-6.3 (although the original Tamron version of the latter is a bit cheaper). So how does it stack up against its rivals in this popular area of the market?

Headline features

  • 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 (OS) system, including Pentax and Sony versions.
  • Hypersonic Motor (HSM) focusing

Angle of view

The pictures below illustrate the focal length range from wide to telephoto (on Canon APS-C, 1.6x).

18mm (29mm equivalent) 250mm (400mm equivalent)

Sigma 18-250mm f/3.5-6.3 DC OS HSM specifications

Street price • $530 (US)
• £400 (UK)
Date introduced March 2009
Maximum format size APS-C/DX
Focal length 18-250mm
35mm equivalent focal length
• 27-375mm (1.5x DX)
• 29-400mm (1.6x APS-C)
• 31-425mm (1.7x Foveon APS-C)
Diagonal Angle of view (APS-C) 74º - 6º
Maximum aperture F3.5-6.3
Minimum aperture F22-40
Lens Construction • 18 elements / 14 groups
• 4 SLD glass elements
• 3 aspherical elements
Number of diaphragm blades 7, rounded
Minimum focus 0.45m
Maximum magnification 0.29x
AF motor type • Micro-type Hypersonic Motor
Focus method Internal
Image stabilization • Yes; 4 stops claimed benefit
• Automatic panning detection
Filter thread • 72mm
• Does not rotate on focus
Supplied accessories* • Front and rear caps
• Petal-type Hood
Weight 628 g (22.2 oz)
Dimensions 79 mm diameter x 101 mm length
(3.1 x 4.0 in)
Lens Mount Canon, Nikon, Pentax (KAF3), Sigma, Sony

* Supplied accessories may differ in each country or area