Sigma 18-200mm f/3.5-6.3 11 DC OS HSM Lens for Canon

Product Information

This lens competes directly in the 'stabilized superzoom' market with the Nikon 18-200mm F3.5-5.6G AF-S VR DX, Canon EF-S 18-200mm F3.5-5.6 IS, and Tamron 18-270mm F3.5-6.3 Di-II VC, all of which which we've reviewed over the past year. Its main advantage at the moment is that it is considerably cheaper than any of these other lenses, making it much the most affordable option for users looking to supplement their collection with a general-purpose travel lens. But in this case, does cheaper also mean inferior, or has Sigma delivered quality on a budget? Headline features High zoom ratio lenses like this Canon optic are often a compromise regarding optical quality. For a lens of this type, the performance holds up very well. At the wider focal lengths, such as 18mm and 28mm, it’s possible to see some distortion when shooting geometric subjects. As you might expect, if you get too close to a normal subject at these wide angle lengths you can also see distortion happening.

Corner shading is fairly well-controlled in the 18-200mm IS. Wide-angle lenses typically show some form of light falloff, and while we see this phenomenon with the 18-200mm, it's not too severe: the corners are only 3/4 of a stop darker than the center, and only when used at 18mm and at ƒ/3.5. At any other focal length while using the lens wide open, corner shading is only 1/2 of a stop. As the lens is stopped down, corner shading falls to 1/4 of a stop by ƒ/8; when using the lens at a focal length of 80mm or greater, there is virtually no corner shading when the lens is stopped down to ƒ/11 or smaller. FTM (Full Time Manual) focusing is not enabled on the 18-200 IS and the focus ring turns during auto focusing.

A white dot on the outside of the hood aids alignment for mounting, and the hood reverses neatly for storage. Set to 18mm, wide-angle performance is good wide open at ƒ/3.5 (sharp in the center, mdoerately soft in the corners), becoming excellent as you stop down to ƒ/5.6, where it is essentially sharp across the frame. Diffraction limiting begins to set it at ƒ/8, though it doesn't impact on sharpness until ƒ/16; even at ƒ/16, we're seeing only 2 blur units across the frame. Using the ƒ/22 aperture setting produces a softer image, at 3 units across the frame. The minimum focus distance of 45cm can be handy for close-up shooting - ISO320, 1/320, f/8, 200mm (35mm equiv – 320mm)

The 18-200mm, like all ''vacation lenses,'' must make concessions to balance optical performance, weight and price. In this regard the Canon lens is not immune. Our copy of the Canon 18-200mm ƒ/3.5-5.6 IS seemed to be very slightly out of alignment, with the effect most noticeable at 18mm (the sharpest region is at the bottom of the frame rather than the center). otherwise, you will see a large bump out of the center with lines straightening again near the corners.

Sigma 18-200mm f/3.5-6.3 DC User Reviews

Nikon has Canon beat here, because Nikon's Gen II cameras automatically correct this and make them a thing of the past, while Canon's cameras, at least up through 2009 as I write this, still can't correct it, and show whatever the lens has in all its gory detail. The range is a bit cramped at the shorter end, making it less easy to set precise framing. It's fine throughout the rest of the range. The Sigma 18-200mm f/3.5-6.3 DC Macro OS HSM can be quite useful as a macro lens if you don’t have a dedicated optic in your kit bag. It has a minimum focusing distance of 39cm / 15.4inches and a maximum magnification ratio of 1:3. Falloff of illumination towards the corners is reasonably well controlled. At 18mm the corners are 1.42 stops darker than the image centre and at 200mm the corners are 1.26 stops darker. Visually uniform illumination is achieved with the lens stopped down by just over a stop from maximum aperture throughout the zoom range.