Sigma 18-50mm F2.8 DC DN Review
The Sigma 18-50mm F2.8 DC DN Contemporary for either Sony E-Mount or L-Mount is a new fast standard zoom lens for Sony, Leica, Panasonic and Sigma APS-C sensor mirrorless cameras, where it provides a 27-75mm equivalent focal length range in 35mm full-frame terms.
The Sigma 18-50mm F2.8 was first announced in October 2021. This lens is designed and made in Japan.
The optical formula is comprised of 13 elements in 10 groups, including 1 Special Low Dispersion (SLD) lens to reduce chromatic aberrations and color fringing and 3 aspherical lenses to limit distortion and spherical aberrations.
This lens has a minimum focusing distance of 12.1cm / 4.8" with a maximum magnification ratio of 1:2.8 at the 18mm focal length.
It features a rounded 7-blade diaphragm which creates an attractive blur to out-of-focus areas of the image and an internal focusing mechanism which means the lens barrel doesn't move.
This lens uses a stepping motor for fast, quiet and precise auto-focusing and full-time manual focus override is also possible.
The Super Multi-Layer coating helps to ensure that flare and ghosting are well-controlled even in backlit conditions.
The Sigma 18-50mm F2.8 DC DN Contemporary lens is is available in Sony E-Mount and L-Mount versions and is priced at £429 / $549 in the UK and USA, respectively.
Ease of Use
Given the fast and constant f/2.8 maximum aperture, the Sigma 18-50mm F2.8 DC DN Contemporary is a surprisingly small and lightweight lens, measuring almost 7.6cms in length and weighing in at a mere 290g / 10.2oz, yet it still manages to maintain a constant aperture of F2.8 throughout the entire zoom range.
This makes it the most compact standard zoom lens in its class, when assessed as an AF compatible, F2.8 constant aperture zoom lens for APS-C sensor cameras.
As demonstrated by the product images, it's a great match for a small camera like the Sony A6000 that we tested it with, where it feels very well balanced.
Build quality is excellent given the affordable price tag. The lens has a plastic shell with a mixture of metallic parts and a compound material, TSC (Thermally Stable Composite), used inside.
It also incorporates a brass bayonet mount that's supposed to be more durable than a normal metal mount. The optical elements are made of high-grade glass.
The Sigma 18-50mm F2.8 DC DN Contemporary feels solid enough in your hand, despite its mostly polycarbonate construction.
The zoom ring is generously wide and has a tactile ridged, rubberised grip band that has a smooth action.
The lens extends by about an extra 4cm when fully zoomed out to 50mm.
The focusing ring is on the narrow side and is located closer to the lens mount, making it easier to locate in a rush.
The Sigma 18-50mm F2.8 DC DN Contemporary features a stepping motor that allows for virtually silent auto-focusing, making it well-suited to video use.
Importantly, the lens is fully compatible with the "Direct Manual Focus (DMF)" system feature of Sony cameras that enables the user to instantly switch between autofocus and manual focus.
Focusing is fully internal but zooming is not, with the length of the lens changing as you zoom from 18mm to 50mm.
In use, we found the focusing system to be quiet, fast and reliable with the lens mounted on a Sony A6000 camera.
The Sigma 18-50mm F2.8 DC DN Contemporary isn't weather-proof, other than the mount having a rubber seal, and it doesn't have built-in image stabilisation, which are the two main concessions that it makes in order to be both affordable and small.
The lens is supplied with plastic lens caps and a plastic flower-shaped lens hood (LH582-02) - there's no lens bag included. The filter size is 55mm.
At the 18mm focal length the angle of view is 76.5 degrees.
At the 50mm focal length the angle of view is 31.7 degrees.
Chromatic aberrations, typically seen as purple or blue fringes along contrasty edges, are well controlled with this lens.
With the Sigma 18-50mm F2.8 DC DN Contemporary wide open at f/2.8, you can see some noticeable light fall-off in the corners. Stopping down helps, although to completely get rid of this phenomenon, you will need to use an f-stop of at least f/5.6 or smaller.
There's quite a lot of barrel and pin-cushion distortion evident in both the JPEG and RAW files which you'll need to correct in post-processing until a suitable lens profile is released for your editing software.
Sunstars and Flare
The Sigma 18-50mm F2.8 DC DN Contemporary produces quite nice sunstars when stopped-down to f/22, as shown below, although it it a little prone to flare when shooting directly into the sun.
The Sigma 18-50mm F2.8 DC DN Contemporary doubles up as a competent macro lens, delivering almost half-size magnification and very close focusing at 18mm.
The close-focus point is an impressive 12.1cm from the film/sensor plane at the 18mm focal length (30cm at 50mm) and it has a maximum magnification ratio of 1:2.8 at the 18mm focal length (1:5 at 50mm).
Bokeh is a word used for the out-of-focus areas of a photograph, and is usually described in qualitative terms, such as smooth / creamy / harsh etc.
One of the reason to buy such a fast lens as the Sigma 18-50mm F2.8 DC DN Contemporary is to be able to isolate the subject from the background.
Sigma have used an iris diaphragm with 7 rounded blades for a fairly pleasing rendering of the out-of-focus highlights.
Below you'll find some examples, but you are also encouraged to check out our sample images.
In order to show you how sharp the Sigma 18-50mm F2.8 DC DN Contemporary lens is, we are providing 100% crops on the following pages.