With DxOMark scores of 11 and 12 points, respectively, the two mounts are identical. (The difference in scores reflects a slight difference in sharpness at 18mm.) Overall, the image quality score is quite low. Unfortunately, super-zooms are not noted for optical quality and this Sigma 18-200 is no exception. Note that the DxOMark score indicates only the maximum score that you can obtain with this camera-lens combination under relatively low-light conditions (150 Lux, 1/60s).
If you look more closely at the bar graphs indicating the minimum and maximum scores attained, you may well be concerned about the overall image quality for this lens. And indeed, such fears may seem justified, given that as soon as one makes use of focal lengths greater than 85mm, the score drops to less than 5. But this phenomenon holds true for most super-zooms, so don’t dwell too much on this point — just keep in mind, again, that super-zooms and high image quality rarely mix.
The strong points of the Sigma 18-200mm F3.5-6.3 II DC OS HSM:
- Good correction of chromatic aberrations (meaning that the new FLD elements had a positive impact).
- Vignetting correct.
The weak points of the Sigma 18-200mm F3.5-6.3 II DC OS HSM:
- Disappointing lack of sharpness, but uniform in the field.
- Not a very bright lens.
- Noticeable distortion, especially from 18mm to 50mm.
Comparing the specs: What effort has Sigma made in terms of ergonomics?
Over the course of 7 years, Sigma has brought out three different versions of its 18-200mm lens, reflecting a fairly significant ergonomic evolution each time:
- At the beginning of 2005, the lens was 78.1mm long, with a diameter of 70mm and a weight of 405g.
- At the beginning of 2007, the lens was 100mm long, with a diameter of 79mm and a weight of 610g. Between the first two versions, the lens was equipped with stabilization (OS), but its size and weight greatly increased.
- At the end of 2011, the lens was 87.7mm long, with a diameter of 75.3mm and a weight of 490g. Between 2007 and today, the lens retained the advantage of stabilization, but reduced both its size and weight.
We also note that the diameter of the filter port changed between the two first versions. This third version returns to the original port filter diameter.
Measurement comparisons among the three Sigma 18-200mm versions
Evolution of the Sigma 18-200mm (from F3.5-6.3 DC to F3.5-6.3 DC OS):
- A very slight loss of resolution.
- A small increase in brightness of around 0.15EV.
- Slightly weaker distortion.
- Stable vignetting.
- Stable chromatic aberrations.
Evolution of the Sigma 18-200mm (from F3.5-6.3 DC OS to F3.5-6.3 II DC OS HSM):
- The resolution stays the same for the Nikon, but noticeably increases for the Canon.
- A loss of light of about 0.10EV.
- Noticeable increase in vignetting.
- Reduced chromatic aberrations.
Further readings for the The Sigma 18-200 mm f/3.5-6.3 DC OS HSM II: A new stabilized super-zoom
To provide photographers with a broader perspective about mobiles, lenses and cameras, here are links to articles, reviews, and analyses of photographic equipment produced by DxOMark, renown websites, magazines or blogs.
February 23, 2012
February 10, 2012
June 10, 2011