Product Description

Large aperture zoom lens designed specially for use with digital SLR cameras with a minimum focusing distance of 20cm (7.9"). This lens is specially designed to suit the characteristics of digital SLR cameras and provides a high level of optical performance. It has a large aperture of F2.8 throughout the entire zoom range, offers superior peripheral brightness as well as a compact and lightweight construction. A maximum magnification of 1:3, making it ideal for close-up photography.

Product Details

• Brand: Sigma
• Model: B000UC5YSQ
• Dimensions: 1.49 pounds

Features

• A minimum focusing distance of 20cm (7.9"), a maximum magnification of 1:3
• Large aperture of F2.8 throughout the entire zoom range
• Special Low Dispersion (SLD) and Extraordinary Low Dispersion (ELD)
• Compact and lightweight lens
• Reduced Ghosting and Flare The super multi-layer lens coating reduces flare and ghost. High image quality is assured throughout the entire zoom range

Amazon.com Product Description
Sigma's 18-50mm EX series macro lens is specially designed for Nikon digital SLR cameras with a minimum focusing distance of 20 cm (7.9 inches), making it suitable for a wide variety of subjects. The lens offers a large aperture of F2.8 throughout the entire zoom range, along with a maximum magnification of 1:3 for close-up macro photography. The interior, meanwhile, incorporates both glass-mold and hybrid aspherical lens technology to deliver superior peripheral brightness and extremely high image quality. Add in Special Low Dispersion (SLD) and Extraordinary Low Dispersion (ESD) glass elements and you have a lens that can correct all types of color aberrations while providing a high level of optical performance at every interval.

The lens also offers a super multilayer lens coating that reduces flare and ghosting, a common problem among many digital cameras. Users will also appreciate the inner focusing system, which provides a fast autofocus speed while preventing the front of the lens from rotating, making it particularly suitable for use with circular polarizing filters and the petal-shaped lens hood (included). The Sigma 18-50mm lens--which measures 3.1 inches in diameter and 3.4 inches long--weighs only 15.9 ounces and carries a one-year warranty.

Customer Reviews

Versus Tamron 17-50, Canon 17-55 [is], Canon 17-85[is], Canon 18-55[is]
I own the best Canon 17-55 F/2.8, but it is also heavy and expensive for risky environments like windy beaches to packed clubhouses. I need an affordable F/2.8 backup, so I bought this Sigma 18-50mm F/2.8 Macro. Having read many account of sigma lens front/back focusing, I have a very low expectation for my lens. Luckily, my fear proves to be unfounded, as my 18-50mm f/2.8 macro is free from rear/front focusing.

[ Biggest Surprise ] = Fast + Silent + Reliable focusing. Even without HSM/USM motor, the AF speed is fast & comparable to my canon 17-55 f/2.8 usm in dim light. Under the same setting, my tamron 17-50 f/2.8's banshee-like micro-motor scream loudly yet failed to find focus after 1 minutes.
+ The build quality is near "L", better than my expensive Canon 17-55 f/2.8 IS
+ Size is very small compare to my gigantic canon 17-55 f/2.8 IS
+ Fantastic MACRO lens on the run

[Disappointment] 18mm F/2.8 "wide open" is softer than Tamron 17-50mm.
- Canon 17-55 f/2.8 @f/2.8 is sharper than sigma 18mm @f/5.6 (no joke!)
- Field of view is closer to 18.5mm or 19mm.

Since I had previously own the tamron 17-50 f/2.8, a canon 17-85is, and a canon 18-55is, here how they compare against one another:

...................................................[ Landscape Sharpness ]

[1] Canon 17-55 f/2.8 IS__amazing sharpess even @f/2.8 wide open
[2] Canon 18-55 IS ______ sharp corners, mild barrel distortion + ca
[3] Tamron 17-50 f/2.8____sharp "when focused", problematic AF, field curvature
[4] Sigma 18-50 f/2.8_____softer wide open than tamron, 18mm behave like 19mm
[5] Canon 17-85 IS_______strong C_A + barrel distortion, soft corners

...................................................[ Bokeh / Out of Focused Highlight ]

[1] Sigma 18-50 f/2.8____ big round circular highlight, no cat's eyed footballs
[2] Canon 17-55 f/2.8 IS__ some cat's eyed football highlight on the edge
[3] Tamron 17-50 f/2.8___ some visible double contours highlight
[4] Canon 17-85 IS______ small f/5.6, 85 has an edge over 55mm in highlight size
[5] Canon 18-55 IS ______ small f/5.6 = smallest highlight, boring photos

...................................................[ Construction Quality ]

[1] Sigma 18-50 f/2.8____ impressive build even at such a low price
[2] Canon 17-55 f/2.8 IS__ [tied] build should have been better for a $1000 lens
[2] Canon 17-85 IS_______[tied] exactly the same build as 17-55 f/2.8 IS
[3] Tamron 17-50 f/2.8___ decent, plasticky, not as good as others above
[4] Canon 18-55 IS ______ plastic mount, front barrel rotate makes cpl difficult

...................................................[ AF Speed in Low Light + Reliability ]

[1] Canon 17-55 f/2.8 IS__ USM + IS + F/2.8 = ultimate
[2] Canon 17-85 IS_______USM + IS, F/5.6 seem to focus just as fast as F/2.8
[3] Sigma 18-50 f/2.8____ Silent, Fast, and Decisive AF even in low light
[4] Canon 18-55 IS ______ silent image stabilization, but louder AF
[5] Tamron 17-50 f/2.8___ loudest motor, indecisive AF in low light

-------------------------------------[ in conclusion ]-------------------------

Sigma 18-50 f/2.8 Macro is jack-of-all-trade, master of none. While tamron is sharper @17mm f/2.8 than sigma is @18mm f/2.8 "when in focused", sigma has superior AF motor that is far more reliable under any circumstance. Sigma is a pleasure to use in real life ownership, free from fousing-worrying that plagued my tamron. Sigma 18-50 f/2.8 is a combination between the reliable yet so-so IQ of canon 17-85is + tamron 17-50's superior IQ, but poor autofocusing mechanics. Highly Recommended!

$429.95 [Canon 17-85IS] poor 17mm IQ, but fantastic AF mechanic + IS
$443.41 [Tamron 17-50] great 17mm IQ, but poor AF mechanic
-----------------------------------------------------------------------
$375.00 [Sigma 18-50mc] decent 18mm IQ + fantastic AF mechanic (no BUT)

Sigma did their homework. Sig18-50 retained good quality from its competitors while shredding the bad, yet it is offer at the lowest price. Competition is wonderful, I'm very happy with my purchased

A versatile lens for a great price
Just another vote of confidence for this lens. (I posted this same review at another online retailer, but since I bought it from Amazon, I decided to post it here, too.)

After learning to love prime lenses, it was time to replace the underwhelming kit lens of my Rebel XT with better quality glass. I looked long and hard for a fast zoom that covered the wide-to-medium range despite the XT's crop factor, and finally settled on the Sigma.

Although I haven't laid my hands on the competition (including a similar 17-55mm f2.8 EF-S from Canon for more than *twice* as much, and the slower 17-40mm f4L), I don't regret my purchase at all. I was a bit wary at first about buying a non-Canon lens, especially after reading a few complaints online about bad samples, but the lens turned out to be just fine.

Edge-to-edge sharpness looks great to me, even wide open, and vignetting doesn't seem to be a problem. I'm not a professional, and don't own any L-series glass, but this is far more than I expected for the price.

The macro ability is also a nice bonus, as is the lens hood and case included in the package. I wouldn't call the lens "lightweight" (since I still prefer small primes when I don't need the versatility), but it's still a reasonable fit on the diminutive XT body.

I'm not crazy about the slight sparkle in the powder coat, but hey, that's hardly a complaint. All in all, I couldn't be happier!

Terrific, versatile lens
At ~$600 less than the comparable Canon model, this lens is tough to beat! After several hundred shots, it's a keeper for me. I debated between this zoom range and 24-70mm, but found that 24mm was just not wide enough for my 1.6x crop Rebel XT, especially for crowded rooms and landscapes. 50mm (80mm FF equivalent) has been fine for most portraits and that zoom combined with large aperature produces nice bokeh. F2.8 makes it terrific for existing light use, though I do still find my 430EX flash necessary sometimes. I find the lens to have good sharpness at f2.8 throughout the zoom range, and at f4.0 and above it's very sharp. Colors are great. I have had no trouble with flare, or fringing, though I haven't pushed it hard in this respect. Sigma seems to have corrected the flare and CA issues with the first version of this lens. Though it's not a true 1:1 macro, I have found the macro function very useful and lots of fun. That said, the extremely small depth of field with f2.8 and macro has exposed my need for a good tripod! Build quality seems to be very good; zoom and focus are well damped. Autofocus seems accurate to me while being fast and quiet. Highly recommended.

[...]