What third party lens have you tried/bought, and how would you rate it?

With the high cost of Canon lenses, do you have a third party lens you would recommend? Or, maybe one you would advise not buying?

I have a Sigma 50-500 OS. It showed up with non-functioning AF and I sent it back for repair vs. returning. They did a great job of calibrating and if it wasn't the size of a small bus, I would leave it on the camera more. It's a great long lens

I think all brands have their stars and dogs. Trying to answer a question about all brands seems impossible, IMO. Yes, 3rd party lenses can be great and often even better than a Canon lens. I have way more 3rd party lenses than Canon.

I have a Tokina 12-24 that has worked very well for me. I think the Canon 10-22 is probably a better choice but the price difference at time of purchase was a deciding factor.

I can't afford good glass right now and needed a medium range lens. I bought a Tamron 55-200mm for £90 UK a few months ago and at first I thought I'd wasted the money. But recently I was at a small music festival, fully intended to get up close and use my Nifty 50 ( another cheap lens but does the the job for me ) until I realised that the "pro" festival guy was blocking all of my angles along with everyone else's.

So I stuck my cheap Tammy on and could stand back and zoom in on the performers ( and cut out the shot blocker ). It was outdoors so the light helped. Not brilliant results but better than coming home with nothing.

As to rating it, worth £90 for the kind of shots I used it for, but not fast enough for sports or wildlife stuff.

My next lens will probably be a Sigma 10-20mm, a friend uses one with his Nikon and the results look great.

Tokina 19-35, $50. Worth every penny of it. Just.
Sigma 70-200 f/2.8 OS HSM, used $750. Almost Canon performance at 1/3 the price.
Tamron 28-75, used $320. More than pleasantly surprised. Better than any review I read.

Vivitar Series ONE 70-210 f/3.5, used $99. One of the best bargains I've ever gotten. Fantastic lens.
Yashica 50mm f/1.9 MLc. Came free on a $20 Yashica body. Excellent glass.
Vivitar Series ONE 28-105. Don't remember cost, maybe $50. Excellent lens with macro function.

Sigma 50 1.4. I picked it up used off eBay. It's been a very good performer, with a solid build and good but not super fast AF. I've also owned the Tokina 12-24. It was also a very good lens, it was built like a tank, very sharp, and in general performed very well, the focal length wasn't for me, so I sold it.

I have had a ton of them...the low end ones are usually pretty crappy. But, I would say the higher end ones (which cost about as much as a mid-range Canon) are right up there with the best Canon has to offer, except for maybe the tank-like build quality of the L lenses...I would not hesitate to buy a top-shelf third-party lens based on the fact that it's not Canon.

As of now I have a Sigma 17-50mm f/2.8 and a Sigma 120-400mm. I like both very much. I use the 120-400 for sports shots, mostly surfers and have had some award winning shots in local contests and galleries. Much better than many of the reviews rate it. In the past I had a Tamron 28-75 f/2.8 which I though was an outstanding lens.

Tamron 17-50mm 2.8 (non-vc)
Rokinon 14mm 2.8

have a Tamron 18-270 for vacations too.

What do you normally shoot? what range do you prefer?

Very recommended:
Sigma 35
Sigma 30
Sigma 17-70 OS

Didn't particularly like:
Sigma 150-500 OS
Sigma 18-200 OS

Sigma 17-50mm f/2.8mm (vs efs17-55mm) image quality just as good, closer focusing, cheaper, longer warranty, lens hood included.

I tried the Sigma 10-20, Sigma 50-500, Tamron 17-50, Sigma 150 macro
All good price/quality but moved to FF, macro wasnt my thing and 50-500 had a dreamrange but unsharp.

Finally I ended up with only one 3rd partylens to upgrade my Canon 17-40,16-35 II :
the Tokina 16-28 2.8, half the price and better than 16-35 II, according to Ken Rockwell it's as good as the legendary Nikon 14-24 so a keeper!

I have the Sigma 8-16 mmm, 85mm, 18-250mm, 150-500mm. I'm quite satisfied with Sigma products

All recommended.

Sigma 50-500mm OS
Sigma 100-300mm f4
Sigma 70-200mm f2.8 OS
Sigma 12-24mm HSM
Tamron 17-50mm f2.8 VC