Sigma 18-50mm lens - has anybody ...

Started Apr 21, 2005 | Discussions thread
Jon Clayton Regular Member • Posts: 475
Not sure about your assertion

ericN2 wrote:

the old story naturally - you cannot expect EVERYTHING as good in a
non-marque lens - after all , that's why they're cheaper

I don't agree with this comment. Sigma, I'm sure, wouldn't agree, either. The reason for the quality difference, where there is one, is nothing to do with the brand, but is more to do with the market. If you had two lenses positioned the same in the same market, the Canon would be more expensive as you pay for the name, but there is no real reason why it should be better.

However, if you compare L glass with non-L glass, the L would likely be better as this is aimed at a different market (i.e. pro). This is true within the Canon range as well as with other manufacturers.

Compare the 18-50 Sigma (not the f2.8) with the Canon non-usm 18-55, and in terms of quality there will be little difference. But generally Sigma don't aim to have the same products as Canon, as this would put them in direct competition and it's better that they offer an alternative.

e.g. The Sigma 70-200 f2.8 is positioned as a (slightly) lower quality lens than the Canon 70-200 f2.8L to capture the people who want a fast lens but don't want to pay L prices, and don't mind losing some of the features, such as weatherproofing.

The Sigma 18-50 f2.8 offers a wider range than the Canon 17-40L and a larger aperture - again aiming at a different market. In this case I don't think you could say one is better than the other.

I think if you have a bad version, Sigma would want to know about it.

BTW, I have the 17-35 Sigma and the focus ring has loosened now, but was, as you say, stiff to start with.

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