Sigma 20-40mm f/2.8 EX DG Aspherical
(From Sigma lens literature) Sigma has created a new 20-40mm lens with f/2.8 throughout its zoom range, from ultra-wide 94.5 degree to near-standard 56.8 degree angle of view, allowing photographers to shoot more creatively from various angles and zoom perspectives. With a fast f/2.8 maximum aperture, superior peripheral brightness is ensured. This lens is perfectly suited for indoors, even in dim light. These features also make this lens desirable for use with Digital SLR Cameras.
The 30cm minimum focusing distance is useful for closeups, giving photographers plenty of capability to use the zoom to adjust composition and concentrate on detail. Maximum magnification is 1:4.6. A short focus distance and a minimum aperture of f/22 provides greater depth of field.
Aspherical lens elements in front and rear lens groups compensate for astigmatic and spherical aberration, respectively. By reducing aberration to an absolute minimum, this lens overcomes a major impediment to zoom lens performance.
Among the practical high-performance features of the lens are DF (Dual Focus) mechanism for optimal handling stability during autofocus operation; a wider-than-conventional focus ring for superior manual focusing operation; and an inner focusing system that eliminates front lens rotation during focusing, and allows use of the standard petal-type hood accessory, which is excellent at blocking out extraneous light.
Sigma 20-40mm f/2.8 EX DG Aspherical User Reviews
10 out of 10 points and recommended by RRJackson (6 reviews)Excellent optics, very useful range of focal lengths.Screw-drive. Large 82mm filter threading.
This lens is something of an anomaly. Nobody else that I'm aware of makes a lens that covers this particular range. The closest thing I can think of is the Olympus 11-22mm (which with their 2x crop becomes a 22-44mm). This range of focal lengths is extremely useful to me. Most wide zooms go wider than this, but they don't go all the way to 40mm on the tele end. I'm not a huge fan of superwide zooms, but I love shooting "normal" at around 40mm. Being able to go wide when things get tight is lovely. By keeping the ratio down to 2:1 Sigma didn't have to make any real optical compromises. All in all this is a perfect "walking around" lens, IMO.reviewed December 16th, 2008 (purchased for $279)
The build quality is excellent, the optics are wonderful and the overall size of the lens is just about perfect. I'd whine about the big filter threading (82mm), but I already had a UV and polarizer in 82mm threading, so it was a non-issue for me.
Sigma has discontinued this lens and it's a pity. I'd love to hear that they're reintroducing it with one of their HSM motors. I think this got lost because it wasn't a range that was ideally suited to crop-sensor cameras, but now that there are a few affordable options out there in full-frame cameras maybe it's time for Sigma to bring it back. Nothing wrong with the original, though. I'm certainly happy with mine.
9 out of 10 points and recommended by rainerknappe (24 reviews)good optics - beautiful lensCAÃÂ´s and a bit heavy
I like this lens, its a very good alternative to my brilliant Tamron 17-50 2.8 (which I use with the Canon 20 DA). The price was really nice specially offering a beautiful design and construccion. I use this lens at my Pentax K 10 and its a really perfect combination - sharp from f 4.5, only little distortion and a bit more cornershading at 20mm and specially beautiful colours - highly recommended!reviewed May 18th, 2007 (purchased for $410)
9 out of 10 points and recommended by ray_lam5 (1 reviews)Sharp at all focal lengths, little distortion at 20mm , excellent build qualitySoft wide open, quite big
Having owned this lens for a year now and having read all the reviews posted on other sites I feel this lens has been overlooked somewhat due to it not being designed for an aps-c sized sensor.reviewed December 27th, 2006 (purchased for $500)
The lens is solidly built with a quality feel to it. I find the camera performs best between F5- F8 but is usable wide open in some instances. Its focusing is not the fastest in the world due to having no HSM and can be discrbed as a little tinny. It however is accurate in good lighting and performs well enough.
The sigma is somewhat of an enigma lens to me, it has so much going for it but i tend not to rely on its fast aperture. It performs best when used for landscapes, architecture and outdoor activities. For low light indoor work i usually rely on primes much more.
This is my jack of all trades lens and finds itself my most used outdoor lens. I would rather have use of the fast aperture in emergency situations then the extra 3 mm of the equivilent canon 17-40F4L. It is a sharper lens at f4 and displays no vignetting or distortion at 20 mm on my APS-H (1D) camera.
8 out of 10 points and recommended by Josstover (4 reviews)Build, Sharp, minor distortionBig and bulky, CA
I bought this lens after selling my nikkor 18-70 kitlens and I did not regret it. It produces clear and sharp images, vivid colors. Little barrel distortion at 20 mm which can be corrected in PS easily. The only problem is chromatic aberration, especially in the edges of the photo. Can be corrected also, but takes some timereviewed August 16th, 2006 (purchased for $180)
9 out of 10 points and recommended by nspur (3 reviews)Optically very good with excellent build qualitySome barrel distortion at 20 mm. Not HSM
Sigma has produced an excellent 2x wide angle zoom lens with the 20-40 f2.8 EX DG.reviewed November 5th, 2005
While the range may not suit users of DX (APS-C format) cameras, it is very useful for full-frame film or digital. By not going ultra-wide, Sigma has avoided the corner softness that often affects such lenses. Throughout the range, sharpness is excellent, contrast is good and colour is good albeit slightly warm. This is also a lens that is not prone to vignetting; there is only very slight vignetting wide open at the wide end and no vignetting at the long end.
A disadvantage is that at 20 mm there is some barrel distortion but it is not excessively significant. In Photoshop CS2 is is necessary to correct the distortion by 1% to 2%.
Auto-focus is accurate. This lens does not have a High Speed Motor and consequently there is no full-time-manual focusing when in auto-focus mode. To implement manual focusing youhave to pull the focus ring towards you and also set the AF/MF switch to MF. Despite the lack of HSM, focusing is fast.
I would highly recommend this lens to anyone looking for a zoom lens in this range.