In article , David Dyer-Bennet
wrote:

That's OK. Most of us rarely take Sigma seriously. Except for the
occasional good lens, most of their stuff is crap.

Sigma is one of the most aggressive lens companies lately, and has made
some outstandingly good lenses. I've never had a bad lens from them.
(Then again, I've chosen all my lenses, from them and others, after
considerable research.)

you must be incredibly lucky. most people need to go through 3 or 4
copies of a sigma lens to get one that actually works properly and is
not decentered or has other problems.

I've never heard anybody claim it's *that* bad, and none of the other
Sigma owners I know have had bad problems.

they're either very lucky or blind to the defects.

as for aggressive, i suppose you could call it aggressive when they
stole nikon's stabilization patents to use it for their own lenses.
unfortunately for sigma, they're being sued by nikon. they also stole
canon's ef protocol for their own sigma mount lenses. nice honest
folks. not.
http://www.imaging-resource.com/NEWS/1306345284.html

I'm really against the ability to patent lens mount interfaces anyway.

the lens mount patents have long expired. sigma mount lenses are
nothing more than sigma's canon mount lenses with a slightly modified
pentax mount plate. a lot of sigma camera owners modify canon lenses or
the camera itself so they're not stuck with only sigma lenses.

on the other hand, infringing nikon's stabilization patents is a whole
'nuther ball game. minolta did something similar by infringing
autofocus patents and paid a hefty sum.
http://www.nytimes.com/1992/02/08/bu...t-must-pay-hon
eywell.html?pagewanted=all

(Happy owner of Sigma 105/2.8 macro, 12-24/4.5 full-frame,
120-400/4.5-5.6).

sigma macros are mostly ok, however, the 12-24 is not that great. the
120-400 is junk, as is its almost identical twin, the 150-500.

The 120-400 routinely gets better marks than the Nikon 80-400, which was
the other primary candidate. And was several hundred dollars cheaper.
It's not of course as good as the Nikon 200-400, say -- but my budget
doesn't go anywhere near that neighborhood.

the nikon 80-400 is old and not particularly good. it's *long* overdue
for replacement. the nikon 70-300 vr is as good or better in the common
ranges and it's autofocus is much faster too. the downside is it only
goes to 300 but that's not a big deal since the 80-400 was soft by 400.

the nikon 200-400, on the other hand, is in a class to itself. it's an
outstanding lens, and expensive too.

fi you can get a working sigma 120-400 then it might suffice but the
chances are very high it will fail.

My main lenses are the Nikon 24-70/2.8 and the Nikon 70-200/2.8 (VRI,
though), but when I went back to full-frame somewhat unexpectedly I lost
both my long end (70-200 no longer had 300mm FOV) and my short end (the
Tokina 12-24 was DX), and I desperately needed to do something.

those are all very good lenses, including the tokina. have you
considered the nikon 14-24? that is also an outstanding lens.

lensrentals ceased carrying most sigma lenses because of constant
problems. the 120-400 and the 150-500 had a nearly 50% failure rate,
but at least you didn't get the 120-300 with its very impressive 90%
failure rate.
http://www.lensrentals.com/news/2008.09.20/lens-repair-data-10

Yep, I just mentioned that (without the link, thanks for being more
specific) in another message. I'm not working them professionally. In
the past I've had excellent results with Soligor, Vivitar, Tamron, and
Tokina lenses.

except that lensrentals had failures out of the box. worse, sigma
refused to repair them, citing 'user damage.' rather amusing for a lens
that never saw any users.