Sigma 15mm f2.8 vs Canon 17-40 f4

[Pricer]

Hey folks,

Im in the process of buying a wide angle/fisheye as my 24-105 doesn't give me the view I'm after. I've narrowed it down to two options, the sigma 15mm f2.8 and the canon 17-40 f4.

I shoot a lot of action sports which is what i will be using the lens for the majority of the time. I've found both of these second hand for £350 in excellent condition with 6 month warranty. My only concern is that after reading up a few reviews of the sigma, the auto focus is alot slower that the canon. When shooting downhill races I'm shooting in Al Servo mode about 90% of the time. Has anyone had/using this lens and what is it like when shooting in Al Servo focusing?

Any advice will would be great!

Cheers
Dave

 

[StewartR]

My advice is that you need to decide whether you want a wide angle or a fisheye. They're two very different animals.

 

[seriousrikk]

The difference between 15mm on a fisheye and 17mm on a wide angle is massive.

I wouldn't worry about autofocus speed on the fisheye, as long as it stays near infinity it will be fine. Before I bought the Canon I tried the Sigma - hated the fact that the focus ring moves during autofocus. For me, considering I use servo at gigs, it was a deal breaker. Hence why I got rid and picked up a used Canon.

 

[a1ex2001]

If you stop the fisheye down a little and focus around infinity everything will be in focus anyway!

As Stewart said though the two lenses you are comparing are very different beasts so decide what you want then buy the lens that delivers that!