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February 04, 2007
[ SIGMA DC 18—200MM ZOOM LENS ]
Sigma DC 18-200mm zoom lens
Price: $500 (Pentax, Nikon or Canon mount)
Recommended
The low-down: This lens has a film-equivalent zoom range of 27 to 300mm, wide enough for architecture shots in narrow streets and long enough for wildlife photography.
dpexpert has expressed some scepticism in the past about these improbably long zooms but we have to admit that Sigma has produced a useful lens albeit with some compromises.
This lens is only for digital single lens reflex cameras and that makes the design and manufacture a little easier than for film cameras. The digital sensor is smaller than a 35mm film frame so the area of glass doesn’t need to be as great. Even so this is a slow lens -- f3.5 at the wide angle end, which is not bad, but only f6.3 at the telephoto end.
Distortion is noticeable. Both barrel (at the wide end) and pincushion (at the tele end) are apparent.
Focus can be slow on low contrast subjects and mechanically noisy. The lens produces a warm colour cast on images -- ideally a lens should be colour neutral.
Like: Construction quality is good and the lens is amazingly compact. The zoom mechanism has sufficient friction that the lens doesn’t slide out when it is held vertically which is an annoying tendency in some kit zooms.
Dislike: The slow focus and the warm colour.
Verdict: There is an objective scientific review of this lens on the German fotozone site. Their conclusion is that the lens involves the compromises to be expected in such an ambitious zoom range in such an inexpensive lens.
While the lens is recommended for its combination of versatility and reasonable price we would still urge consideration of two or more shorter range zooms covering the same focal lengths. The excellent Sigma 17-70mm lens is a good starting point, plus a Sigma 180mm prime for the times when a longer reach is needed. You know what they say about free lunches.
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Posted by terry at February 4, 2007 11:59 PM
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