APS-C sized imageLenses that create APS-C sized image are designed for digital only. They cannot be used on cameras that have image sensor larger than the APS-C format. These lenses are not suitable for film cameras either. No Ultrasonic AFLenses with ultrasonic focusing mechanism tend to be quiter and faster than traditionally focusing lenses. One or more Low Dispersion lens element is usedLow Dispersion lens elements help to reduce chromatic aberration. Not stabilizedImage stabilization helps to reduce blur caused by hand shake, especially at high focal length or in low light situations. Image stabilization can give 1 to 3 stop advantage over none stabilized lens, based on the reciprocal rule. Metal mountCheaper lenses are usually equipped with plastic mount, while more expensive, professional lenses have metal mount. In general, metal mounts are more durable, and a good thing to have when lenses are changed a lot. When a camera is used mainly with one lens, the material of the lens mount is not that important. Internal FocusingInternally focusing lenses don't change their size while setting focus. The front lens is fixedThe fixed front lens is not rotating during zoom and/or focusing. This allows the photographer to use petal shaped lens hood. Fixed front lenses also make the use of polarization filters a lot easier. No drop-in filter supportDrop-in filters are used in those lenses where either the front lens is too large, or the field of view doesn't permit the use of traditional filters at the front of the lens. Usually bright tele and ultra-wide angle lenses support this filter type. |
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The characteristics of digital SLR cameras were taken into consideration when designing the lens power layout. A Special Low Dispersion (SLD) glass lens element provides effective compensation for lateral chromatic aberration, which is likely to occur with digital SLR cameras. The use of two aspherical lens elements provides correction for various aberrations and makes high quality images a reality throughout the entire zoom range. A Special Low Dispersion (SLD) lens and two aspherical lens elements provide excellent correction for all types of aberrations. Super Multi Layer (SML) coating gives the best color balance and reduces flare and ghosting from which digital cameras tend to suffer. This lens has a minimum focusing distance of 28cm throughout the entire zoom range which is very convenient for close-up photography. The lens is equipped with an inner focusing system. This lens has excellent correction for vignetting which is a common problem of large aperture lenses. Its new design ensures superior peripheral brightness.
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| Available mount(s) | Canon EF, Nikon F, Pentax K, Sony / Minolta A, FourThirds, Sigma |
| Application(s) | Portrait, Landscape, Architecture |
| Category(s) | Standard zoom |
| Multiplier | 1.5× |
| Stabilizer | no |
| Focal length | 18 - 50 mm (2.8× zoom) |
| Lens construction | 15 elements in 13 groups |
| Angle of view |
35mm: N/A digital: 69.3-27.9° |
| Number of blades | 7 |
| Maximum aperture | wide: f/2.8 tele: f/2.8 |
| Minimum aperture | wide: f/22 tele: N/A |
| Minimum focusing distance | 28 cm |
| Magnification | 0.2× |
| Filter size | 67 mm |
| Size | ∅ 74.1 × 84.1 mm |
| Weight | 445 g |
| Notes |
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| AF speed | N/A |
| AF sound | |
| Internal focusing | yes |
| Internal zoom | N/A |
| Fix front lens | yes |
| Mount type | metal |
| Weather sealed | N/A |
| Drop in filter | no |
| Ultrasonic AF | no |
| APS-C sized circle | yes |
| Low dispersion lens element | yes |
| Hard case | N/A |
| Soft case | included |
| Lens hood |
included printable lens hood |
| Tripod adapter | N/A | Discontinued | yes |
Nov 24, 2004
I have a Canon 20D, and I have had these lenses:
Canon 50mm/1.8 (my reference standard for the best lens performance I can reasonably expect)
Canon 28-135 IS
Canon 28/2.8
Sigma 18-50/2.8
Canon 18-55 EFS
I have found that the Sigma 18-50/2.8 is the lens I keep on my camera most of the time. It has very good color, contrast, sharpness, saturation, and low distortion and aberration. By contrast to the 18-55 kit lens that came with my camera, the Sigma is in a whole different class. I would compare it favorably with my Canon 28/2.8 prime lens. I have never used a prime lens wider than 28mm, so I can't speak as to what the distortion is like at 18mm compared to a prime, but in general I am very pleased with the Sigma.
I find it has better dynamic range than the Canon 28-135 did; I can get better textures and ranges of intensity.
For the highest quality, I always go to my Canon 50/1.8, but in walking around and general shooting, I use the Sigma.
I was interested in the Canon 17-40L, but from what I have seen there is not a lot of difference in the quality from that lens and this one. Perhaps a little less distortion, but nothing you would notice unless you are taking pictures of brick walls.
Dec 26, 2004
This lens is soooo sharp. I returned a sigma 17-35mm EX DG HSM. The 17-35mm was a good lens with superb build. The 18-50mm f/2.8 is a great lens with good build. HSM would be nice and so would full time manual focus. Having said that. The focus is fast but not silent. However it is not loud either. And the auto focus is sharp, so I haven't had to use manual focus. It is so light that at first you think hey is the build cheap? No it isn't! It works well on my EOS 20D. If Sigma could make this lens 17-85mm they would sell a million of them. There is a lock for zoom creep but I never use it because there is no zoom creep. Oh yes the color and contrast are also great.
Sep 16, 2005
Image stabilization is the new hotness in lens design, but being an old-fashioned sort, I went on a search for a lens with a wide maximum aperture instead. Sure, IS and VR give you the ability to hand-hold week long exposures, but what if your subject is moving? Amazing what a difference that extra stop can make when you need to capture action in low light. Plus, the AF system works better, and the viewfinder is brighter.
Cost, however, is what drove me to this lens. Due to financial constraints, I could afford no more than $500 for a lens for my 300D, which knocked the Canon L-series glass out of contention. After looking at the Tokina and Sigma 28-70 F2.8 lenses, I discovered this lens was in the pipeline and held out for it.
It's not a replacement for the Canon L-Series lenses. That's the bad news. The good news is that this is possibly the PERFECT advanced amatuer lens. Good optical quality, though a little soft at F2.8. Focuses quickly, and "wanders" less than other EF-mount lenses I own (18-55mm EF-S kit lens; low-end Sigma 28-90). The wide aperture allows for auto focusing in what feel like "no light" situations.
Strengths:
Quick focus, little focus "wander", good build quality, included sunshade and case, relatively light weight and small size
Weaknesses:
Works only with APS-C image sensors, a little soft at F2.8
Jan 2, 2006
I am very happy with my purchase of this lens. I bought it to replace my Rebel XT's 18-55mm kit lens, and it compliments the camera very well. The greatest strength of this lens is its remarkable sharpness. Even 100% crops retain their quality. Shots are even acceptable at f2.8 (better than or equal to the kit lens at f8+), and past f8 the lens is stunningly sharp. I uploaded some shots and 100% crops to amazon in order to illustrate my point. The sharpness of this lens is easily comparable to Canon's 17-40, which says quite a lot.
The corners are not as sharp as the center, especially in wide angles. Outside of the center, the 18-50 is also prone to chromatic abberations/fringing but not worse than almost any other lense. Barrel distortion is present at 18mm but much better than the competition (ie, the 17-40L and 17-85 IS).
Color saturation is good- not as impressive as the Canon 17-40 but still perfectly adequate and very good with a slight software sharpening boost.
The only true negative I have found is a propensity for light lens flare. Even when the sun is out of frame by 20 degrees, flare can still occur. (note that this flaring is not major, and I have often not even noticed it until the second or third time I come back to a picture) I have also noticed flare from street lamps in 10+ second night shots. The lens comes with a decent hood (as well as a pretty nice soft case) in order to help prevent flares. However, I have noticed flaring in cases where the sun was so indirect I never would have thought to attach the hood. The lens cap also cannot be accessed while the hood is on, which is a frustrating design quirk. While, even in the best lenses, flare is not totally avoidable the 18-50 flares much more frequently than other lenses I have used. I don't know if this is an issue with the internal optics or the coatings used on the lens.
Even considering flare problems, I would buy this lens again without a second thought. Its only direct competitor in quality is the Canon 17-40L, which is more expensive, shorter in range, has a narrower max aperture and worse barrel distortion. I am extremely happy with almost every shot this lens generates, and its moderate price makes the 18-50 f2.8 a great companion for the Rebel XT.
Jan 27, 2007
I currently own this lens. It's a great all-purpose lens and I think it's very fresh even at 2.8. Razor sharp from f4-f11. Very comparable IQ to Canon L lenses. The only real differences are the Canon L's weather sealing and quieter/faster autofocus. Is the difference worth $700+ to you? This lens comes with me to every wedding I shoot. You tell me!