In article , Chris Malcolm
wrote:

If Sigma lenses are as bad as they say, I'm surprised that none of the
Sigma lenses I have or are owned and much appreciated by several of my
local photographer friends have given us any problems. That good luck
should have stretched so far if most Sigmas are crap seems stretching
luck and probability rather far. I note when reading lens reviews that
some Sigma lenses seem to have been notoriously troublesome, while
some others seem to be well regarded for build, optical quality, and
consistency.

I wonder, could it possibly be the case that some Sigma lenses are
good and some are bad, and you can find out which are which by
checking reviews etc? Could it possibly be that lensrentals have
fallen out with Sigma over some service issues and are trying to get
their own back? What other lens rental agencies report similar
problems?

sometimes you can get a decent sigma lens but it's a crap shoot.

the reality is that most people don't care. they buy sigma because it's
cheap and they're happy.

very, very few people pixel peep or take pictures of test charts to see
if their lens is functioning properly. if their photos look reasonably
good, then as far as they're concerned, the lens works fine.