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

The Sigma 18-250mm f/3.5-6.3 DC OS HSM was first declared in Jan 2009, becoming available to buy in Goal the same season. It’s basically an upgrade to the 18-200mm f/3.5-6.3 DC OS HSM, with a long 13.9x zoom capability variety providing it nearer in achieve to the 18-270mm F3.5-6.3 VC from Sigma’s excellent opponents Tamron. Remarkably, the enhanced telephoto variety has been covered with hardly no alternation in dimension (Sigma’s requirements observe a simple 1mm increase length), and only a moderate surge in bodyweight.

Sigma 18-250mm F3.5
Sigma 18-250mm F3.5

All of these developments over its forerunner come at an amount – the 18-250mm expenses some $100/£110 more than the 18-200mm OS during plenty of your persistence of composing, and $220/£180 more than the mature, non-OS 18-200mm (which of course benefits stabilization on Pentax and Sony models bodies). But it’s still a bit less expensive than many of its immediate opponents, such as the Nikon DX 18-200mm F3.5-5.6G AF-S VR II, the Cannon EF-S 18-200mm F3.5-5.6 IS, the Tamron 18-270mm F3.5-6.3 Di-II VC, or the Sony models DT 18-250mm F3.5-6.3 (although the unique Tamron edition of the latter is a bit cheaper).

Headline Features

  • Approx: 28-400mm comparative central duration range; F3.5-6.3 highest possible aperture
  • Available for Cannon, Nikon, Pentax, Sigma and Sony models installs (APS-C/DX structure DSLRs only)
  • In-lens Visual Stabilizing (OS) program, such as Pentax and Sony models editions.
  • Hypersonic Engine (HSM) focusing

The 18-250mm OS is a normal upper-mid-range Sigma style, which means a solid-feeling lens with a nice-looking matte-black finish and sleek function of manages. In common with other contacts it in its category, the install is steel and the gun barrel is constructed from light and portable but good-quality plastic materials. Like all superzooms the Sigma comes with a ‘double-trombone’ style for expansion of the top part lens team on cruising, but uncommonly it also uses a identical procedure for shifting the back team internal. The lens is quite identical in size to Tamron’s 18-270mm F3.5-6.3 VC (although it doesn’t increase quite so far at full tele), but clearly bulkier, perhaps showing a greater use of steel in the gun barrel development.

Sigma 18-250mm F3.5 Body And Design
Sigma 18-250mm F3.5 Body And Design

Three changes are placed down one part of the gun barrel in simple achieve of the right thumbs. At the top is a zoom capability secure change, which is a little bit better-placed than that on the Tamron 18-270mm like the other contacts in this category, this only performs at 18mm. Below it are the manages for the concentrate and picture stabilizing mechanisms; these two changes are large and simple to operate, especially in comparison to those found on the Cannon and Nikon 18-200mm contacts.

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Lens body elements

  • The lens comes in editions for Cannon Nikon, Pentax, Sigma and Sony models DSLRs; our review example was in the Cannon EF install. This view reveals the somewhat uncommon ‘double trombone’ procedure which is used for shifting the back factor on cruising.
  • The narrow line is 72mm. It does not move on autofocusing, which should please narrow users.
  • The bayonet-mount bonnet is provided as standard, and clicks of the mouse favorably into place on the top part of the lens. It’s made from dense plastic, and functions ribbed moldings on the inside to reduce insights of wander light into the lens. white dot on the outside of the bonnet helps positioning for increasing, and the bonnet turns around nicely for storag
  • The zoom capability band has a 32mm extensive ribbed rubberized hold, and moves 80 levels anti-clockwise from extensive to telephoto (the same way as Cannon contacts, but reverse to Nikon, Pentax and Sony’s). The experience is sleek and even, in noticeable comparison to Tamron’s 18-270mm VC.
  • The concentrate band has a 10mm-wide hold, and moves just 45 levels clockwise from infinity to 0.45m, related Canon and Sony models contacts but reverse to those from Pentax and Nikon. A basic range range is noticeable in feet and metres. The concentrate band moves a little bit past the infinity position, and moves during auto-focus.
  • s. At the top of the gun barrel (towards the right of this picture) is the zoom capability secure, which as regular performs at 18mm only. Below that sites the auto/manual concentrate method selector, with the picture stabilizing on-off change at the bottom.
  • The numbers match each of the central measures noticeable on the zoom capability band except for 18mm and 24mm (at which roles this sleeve is not visible).

Sigma 18-250mm F3.5 DC OS HSM Test Results

The Sigma 18-250mm F3.5-6.3 DC OS HSM acts quite much like the mature 18-200mm in our studio room assessments, and therefore has a quite different stability of features to most other superzooms. Distortions is uncommonly low, but this comes at the cost of sharpness – especially towards the telephoto end. Efficiency is therefore somewhat less reliable than any of its immediate opponents, the Canon EF-S 18-200mm F3.5-5.6 IS, the Nikon AF-S 18-200m F3.5-5.6G DX VR, or the Tamron 18-270mm F3.5-6.3 Di-II VC.


Sharpness answers are incredibly combined. Usually for its category, the 18-250mm is most powerful in the mid-range (24-50mm), but then has a pretty disastrous dip in sharpness at more time central actions before rallying a bit at complete telephoto. At almost all central actions (except 50mm), the sides are remarkably smoother than the center of the structure. At its best (24mm F5.6) the lens profits outstanding outcomes across most of the frame; at its most severe (135mm F5.6) it’s very smooth indeed. Overall, like most superzooms, the best possible sharpness is normally acquired an end or two down from highest possible aperture.


We consider falloff to begin with becoming a prospective issue when the area lighting drops to more than 1 quit below the center. Falloff is often low and unlikely ever to be photographically problematic; its dimensions are just 1 quit by 18mm F3.5 (essentially vanishing on avoiding down to F4.5), and at more time central actions it’s too low to be of any issue.


Sigma has handled to keep distortions uncommonly low for a superzoom. Gun barrel distortions at wideangle actions 1.9%, however this is a complicated ‘wave’ distortions with significant area re-correction, of a kind that is relatively challenging to appropriate in application if preferred. At more time central actions the design changes to pincushion, attaining a highest possible of about -1.9% in the 35-50mm variety. Overall, in the same style as the 18-200mm OS, this is rather less excessive than we’ve seen on other superzooms (e.g. the Cannon 18-200mm’s 3.4% barrel distortions at 18mm, or the Nikon 18-200mm’s -2.3% pincushion distortions at 50mm).

Macro Focus

Maximum magnification is 0.38x, achieved at 250mm and a closest focus distance of about 32.5cm, giving a rather tight working distance of just 10cm from the subject to the front of the lens. This can only be attained using manual focus, though; in AF the lens will focus no closer than Sigma’s specified 45cm, giving an image area of 76 x 51 mm at 0.30x magnification (click here for test chart shot). Image quality is reasonable, with central sharpness peaking around F8-F11. The corners of our test chart image are however distinctly soft wide open, and continue to sharpen up on stopping all the way down to F22. There’s visible chromatic aberration, but almost no distortion.


The 18-250mm seems reasonably resistant to flare (although the general invisibility of the sun over the majority of the testing period mans we’ve not been able to get as good a feel for this as usual). With the sun in the frame at wideangle there’s a degree of veiling flare, resulting in an overall loss of contrast, and if you stop right down a few bright flare spots can become visible.

Sigma 18-250mm F3.5 Chromatic aberration
Sigma 18-250mm F3.5 Chromatic aberration

Towards the longer end of the range, we saw few serious problems with flare either. However you can get some veiling flare if you attempt to shoot strongly backlit subjects with the sun just outside the frame, but still impinging on the front element; luckily you can normally see in the viewfinder when this is likely to be a problem.

Bokeh Quality

One genuinely desirable, but difficult to measure aspect of a lens’s performance is the ability to deliver smoothly blurred out-of-focus regions when trying to isolate a subject from the background, generally when using a long focal length and large aperture. This lens can allow you to achieve quite substantially blurred backgrounds, especially at longer focal lengths and large apertures.

Sigma 18-250mm F3.5 Bokeh Quality
Sigma 18-250mm F3.5 Bokeh Quality

The 18-250mm isn’t always the best lens in the world when it comes to rendering out-of-focus areas (although to be fair, superzooms rarely are). For closeups the bokeh is attractive enough, with generally smooth blurring of the out-of-focus regions. More distant backgrounds, however, are often quite ‘busy’, with harsh edges to transitions, and occasional double-line rendition of out-of-focus elements (so-called ‘nissen bokeh’).

Chromatic aberration

The 18-250mm, like pretty well all superzooms, shows significant lateral chromatic aberration at each end of the zoom range. This is visible as strong red/cyan fringing towards the edge of the frame at wideangle, and even stronger green/magenta fringing at telephoto. In the middle of the zoom range there’s scarcely any CA visible at all. The samples below give an idea of how this looks in practice – note these are 100% crops from the most demanding APS-C DSLR currently available, the 17Mp Canon EOS 7D.

Sigma 18-250mm F3.5 Flare
Sigma 18-250mm F3.5 Flare

This CA can be removed pretty effectively in post-processing – indeed on all current Nikon DSLRs except the D3000 it will be automatically corrected in the JPEG output anyway. The examples below give an idea of how effective this can be, using Adobe Camera Raw’s Lens Correction module; the visibility of the fringing is dramatically reduced.

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Sigma 18-250mm F3.5 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)