9 out of 10 points and recommendedFast f/2.8 aperture and flexible zoom range in a small, durable packageNoisy and slower AF than with an AF-S lens
Sigma's 18-50mm f/2.8 EX DC is a wide, constant aperture autofocus zoom lens for use only with digital SLR cameras using APS-C sized sensors. The zoom range is ideal for covering events, going from wide enough to cover a scene or a table of guests, to a 'mild' telephoto good enough for portraits, so it is currently my most used lens. In the studio, it can find use for full-body portraits and groups, and its image quality holds up to scrutiny.reviewed May 2nd, 2006 (purchased for $450)
The Sigma 18-50/2.8 is an EX lens, which denotes high-quality construction. The lens feels solid and the weight is considerable for its size, making it feel packed, and it is, with fast glass. The special Sigma EX 'crinkle' finish is a love-it-or-hate-it look but has the advantage of being not easy to scratch. It has a 67mm filter thread. The lens mount is metal.
AF speed, since it does not have micromotors, is dependent on the camera body being used, but it is fast enough on a Nikon D50. AF action is unfortunately also noisy being without the benefit of Silent Wave Motor technology.
The lens focuses very close, closer than the Nikon 18-70mm (kit lens), but it is not a macro lens.
The Sigma is sharp through the zoom range, especially in the center area. The sharpness looks good at f/2.8 and excellent at f/4 and smaller. Light falloff shows up at the large apertures but is less noticeable past f/4.
I wrote a more complete review here: http://www.gadget-hack.com/2006/04/sigma-18-50mm-f28-ex-dc-af-lens-user.html
9 out of 10 points and recommendedFast f/1.4 aperture, sharp at the large apertures and smaller, compact and lightTypical price makes it hard to justify over the f/1.8; maybe not as durable as other f/1.4 Nikkor lenses
The Nikon 50mm f/1.4 is encased in lightweight yet well-built plastics and some metal components. The lens mount is metal, as is the 52mm lens thread. The focus ring is made of grippy rubber. It has an aperture ring which locks at minimum aperture for mounting on most Nikon DSLRs up to the D100. As with other f/1.4 primes, the lens has a window for the distance scale.reviewed May 2nd, 2006 (purchased for $160)
Sharpness of this lens has been the subject of much debate, especially when put against the f/1.8. I have found it to hold up well in sharpness at the large apertures against the 1.8, and obviously it has the advantage of going a stop faster. It only gets sharper as you stop down to f/4 and up. Contrast does go away as your aperture gets larger but is not a problem.
On its own, the Nikon 50mm f/1.4 D is a great lens for the candid shooter who likes to shoot in natural light. That said, the 50mm f/1.8 D does the same job but at slightly lesser capability. Put it beside the 50/1.8 which is easily half the price, and it becomes harder to justify the cost, but the quality is there for those who will pay the premium for it.
I wrote a more complete review here:
10 out of 10 points and recommendedExcellent image quality, excellent build, excellent VR implementationpricey, shortens focal length when focusing close, max aperture goes down to f/4.8 at closest focusing distance
Impressively, the Nikon 105/2.8 VR shows center and corner sharpness through the entire aperture range. The sweet spot is said to be between f/5.6 to f/11, but inspecting 100% crops did not reveal much loss of sharpness at the larger apertures. This probably has a good deal to do with the ED glass element and Nano Crystal coating showing its worth, but it is also probable that the lens outresolves the 6-megapixel APS-C sensor on the test body (a Nikon D50), so any decrease in sharpness is not as apparent.reviewed May 30th, 2006 (purchased for $875)
Likewise, color and contrast are also consistently well rendered through the range of apertures. The only flaws in this gem are flaring and chromatic aberration, which shows up in high contrast scenes from maximum aperture (f/2.8) and is minimized by f/5.6. This is, however, typical of many large aperture lenses at maximum aperture.
Bokeh is one of the best traits of this lens, pretty much up there with some of the best Nikkor lenses, like the 85/1.4 AF-D. Out of focus areas are smooth, and the 9-bladed diaphragm helps to render out of focus point lights as circles rather than harsh geometric shapes.
My complete review: http://www.gadget-hack.com/2006/05/nikon-105mm-f28g-if-ed-af-s-vr-micro.html
7 out of 10 points and not recommendedSharp at the center at all apertures; close focusingf/2.8 goes away fast; bad CA; priced too close to the Sigma 18-50/2.8
The Sigma 17-70 is not f/2.8 for much of its range. By 24mm you are already at f/3.3, and by 50mm at f/4.2. This is no worse than with the Nikon 18-70 DX, but will leave those with the need for faster apertures slightly disappointed (in truth they would be better served by a constant aperture lens).reviewed June 28th, 2006
The Sigma 17-70 shares the same characteristics as the 18-50/2.8: it is sharp at all apertures at the center, then decreases in sharpness in the corners. Moving into the longer end of the focal lengths, the difference between corner and center sharpness decreases. As is the case with some macro zooms, sharpness at infinity focus tends to be soft. Here it is not bad but not great either. Bokeh is not very smooth but not that distracting. These traits make it a serviceable enough macro lens, as long as you do not need 1:1 reproduction, and a very flexible lens able to deliver sharp photos in general use.
Some flaws in this lens can be found if you look hard enough. Vignetting shows up at the wide apertures, and at the same time contrast suffers noticeably. Also, chromatic aberration is obvious at wide open apertures, and still noticeable even stopping down to as much as f/11 if the conditions are bad enough.
My full review: http://www.gadget-hack.com/2006/06/sigma-17-70mm-f28-45-dc-macro-af-lens.html