Originally posted by Dewman I would suppose that like all mass-produced products, there will occasionally be a lemon, but I think they are few and far between. However, all it takes is ONE and the word spreads like wildfire.
So true. If someone gets a decentered or unsharp copy (or what they think is one) they will repeat the complaint in every second post. (There was a guy here who endlessly repeated complaints about the 55-300.) If it happens to be a professional reviewer (Photozone??), the reputation of the lens can be trashed. But time sorts the wheat from the chaff - or as the saying goes, Truth is the daughter of Time. I think the body of experience with the DA 18-135 (well represented in this thread) is now such that people know it's a very good lens, and there's no reason to think that there is any higher proportion of duds than for any other consumer lens.
Originally posted by normhead Several forum members have had lenses on the lower end of the scale.... there is a lot of room in what manufacturers consider to be "within spec." It doesn't matter what you buy, you have to be prepared to exchange one or possibly two to make sure you get a good copy.
It's a good reason to buy new from an authorized seller.
Originally posted by normhead The Tamron 70-200 is a great example of such a lens
The DA 20-40 Ltd is another example. There seemed to have been production quality issues, particularly early on - exacerbated by its high (excessive?) price at launch. Sandy - who's an excellent judge of lenses - sent his back. But the issues seem to have diminished over time and many users love it as much as the other DA Ltds. More realistic expectations help, as with the DA 18-135: for example, buyers should know that the 20-40 has a lot of field curvature, and that the 18-135 lacks edge/corner sharpness at the long end.