Lens upgrade for Sony Alpha 200?

There are several option for differing reasons, though the main two contenders are:

Sigma AF 17-70mm F/2.8-4.5 DC Macro and Tamron AF 17-50mm F/2.8 Di-II.  Personally I prefer the Sigma (I've owned 3x copies of it and 1x copy of the Tamron).  You can see samples from the Sigma here.  The later OS version doesn't have OS in Sony mount and the Mk 1 version is regarded as sharper than it's successor, but it may depend on your need and budget, but from personal experience it's a superb performer giving excellent results at an affordable price.

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Mark @ Sonolta * Photography