In article <6gk819$cck$1@wolfman.xtra.co.nz>, andrew-ford@nospamxtra.co.nz says...

>Of all the 3rd Part lens manufacturers which have good reputations and which
>don't. I can't believe the difference in price between a "Canon" or " Nikon"
>lens compared to on of these 3rd party lenses. Is there really that much
>difference? Do you own one? Can you comment on this? I'm sure if they made
>"Bad" lenses, they'd go out of business wouldn't they? I'm just curious.

The truth is, most people's standards are not very high, especially
beginning photographers', or those who just want "snap-shot" records.
For these people, "3rd party" lenses are fine (though they rarely
have the resale value of the camera maker's lenses - which is
irrelevant if they are unlikely to be sold soon after purchase...;-).
I have tried a LOT of lenses in the last 30 years (see my "SUBJECTIVE
Lens Evaluations [Mostly Nikkors]" on my web site, under "I babble"),
and the vast majority of "3rd party" lenses have ranged from really
terrible to fair, with only a few rising above that level (only these
were included in my list...). Of these, only a handful approached
*average* Nikkor lens image quality, with NONE exceeding that (or,
another way of puting it is, many Nikkors outperform the few best
"3rd party" lenses I have seen...). My conclusion: with few exceptions,
if you are looking for the best optics and/or resale value, "3rd party"
lenses are a waste of money. If you are not critical of lens
performance and/or your budget is extremely limited (or, if you are
willing to seek out the few good exceptions [mostly 90-105mm macro
lenses, and the 70-200mm or so zooms]), "3rd party" lenses can make
sense.
David Ruether
http://www.fcinet.com/ruether