Sigma AF 18-50mm f/3.5-5.6 DC (Nikon mount) - Review / Lab Test Report
Lens Reviews - Nikon / Nikkor (APS-C)
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Review by Klaus Schroiff, published July 2006

Lens kindly provided for testing purposes by Friedrich Burgwedel!


The Sigma AF 18-50mm f/3.5-5.6 DC is one of those lenses typically sold as a kit zoom often combined with the Sigma AF 55-200mm f/4-5.6 DC and a consumer DSLR. Nonetheless it is also possible to buy this lens independently for just a few bucks. As a DC (Digital Camera) lens it has a reduced image circle only compatible to APS-C DSLRs. Its field-of-view on a 1.5x crop DSLR is equivalent to 27-75mm on full format cameras. The lens is available for all APS-C DSLR systems plus four-thirds.

Note: the product images above show the Sigma in Canon mount

Regarding its price tag you can't expect tank-like qualities but it's actually quite decent by consumer standards without any overly shaky parts. The focus and zoom control rings operate pretty smooth. Typical for most zoom lenses the Sigma extends when zooming towards the long end (see above). The front element of the lens rotates when focusing so using a polarizer can be cumbersome. In AF mode the focus ring is coupled to the AF motor so it rotates during focusing which is a little sub-standard but quite normal in this price class. The lens has no internal AF motor and relies on a slotted drive screw operated by the camera. The AF speed was pretty fine on the D200.

Equiv. focal length27-75 mm (full format equivalent)
Equiv. aperturef/5.3-f/8.4 (full format equivalent, in terms of depth-of-field)
Optical construction8 elements in 8 groups inc. 1 aspherical element
Number of aperture blades7
min. focus distance0.25 m (max. magnification ratio ~1:3.5)
Dimensions68 x 62 mm
Weight250 g
Filter size58 mm (rotating)
Hoodsupplied, barrel-shaped
Other features-