Sigma 17-50mm F2.8 V Canon 17-40mm F4

Hi,
I'm in the market for a landscape/walkaround lens. I'm considering the Canon 17-40mm F4 and the Sigma 17-50mm F2.8 OS. I'm not interested in the 17-55 F2.8, or any other makes, just those two. I will be using it on a 7d, mostly on a tripod, 90% of its work will be landscape stuff. I have a flash to combat low light situations if needed, but I doubt I will require it in low light situations.
Now I know people slam the Canon on a crop, but what I don't understand is if it's a great lens on FF the with a smaller sensor surely it should be sharp all the way to the corners ?? I do have a preference to the L, I'll be honest. I already have Sigma lens which I'm happy with, and I know the Sigma is getting good reviews, I would like to know how they compare in real world situations..... Comparison pictures would be very helpful if possible.
Thanks in advance.

The Sigma's IQ is equal to, if not better than, the 17-40L; it's faster; it has more reach; it has IS; and it's cheaper!

The 17-40L has internal focus/zoom which is nice but that's about it. Unless you plan on sharing the lens with a FF body, the Sigma is a no brainer.

ktownhero wrote in post #13055432
The Sigma's IQ is equal to, if not better than, the 17-40L; it's faster; it has more reach; it has IS; and it's cheaper!

The 17-40L has internal focus/zoom which is nice but that's about it. Unless you plan on sharing the lens with a FF body, the Sigma is a no brainer.

This. The 17-40 is also weather sealed, I don't know how much a difference that makes to you.

h14nha wrote in post #13055389
Hi,
Now I know people slam the Canon on a crop, but what I don't understand is if it's a great lens on FF the with a smaller sensor surely it should be sharp all the way to the corners ?? I do have a preference to the L, I'll be honest. I already have Sigma lens which I'm happy with, and I know the Sigma is getting good reviews, I would like to know how they compare in real world situations..... Comparison pictures would be very helpful if possible.
Thanks in advance.

you can find plenty of "real world" pics for both lens in the archives or on the web but on a crop model it's not even close
http://www.the-digital-picture.com …omp=0&FLIComp=2​&APIComp=2
or
www.photozone.de

ktownhero wrote in post #13055432
The Sigma's IQ is equal to, if not better than, the 17-40L; it's faster; it has more reach; it has IS; and it's cheaper!

The 17-40L has internal focus/zoom which is nice but that's about it. Unless you plan on sharing the lens with a FF body, the Sigma is a no brainer.

+2.

It really is a no brainer on a crop body.

kin2son wrote in post #13055507
+2.

It really is a no brainer on a crop body.

Unless you go FF some day...

Thanks for the replies guys, I have taken a look through the lens sample threads, I was hoping perhaps someone had done side by sides..... Sigma definately have done their homework on this lens, I think many people will be turning their backs on the L for this lens. F4 isn't a dealbreaker for me as it will be used mostly for landscapes..........
( I have no FF plans btw, I love birding )

h14nha wrote in post #13055598
I think many people will be turning their backs on the L for this lens.

And canon won't really care, because the APS-C market isn't what the 17-40 was designed for. Its an UWA for FF, not a normal zoom for crop.

watt100 wrote in post #13055485
you can find plenty of "real world" pics for both lens in the archives or on the web but on a crop model it's not even close
http://www.the-digital-picture.com …omp=0&FLIComp=2​&APIComp=2
or
www.photozone.de

I don't know ... take a look at at the top link again and you can clearly see fringing (chromatic aberration) on the Sigma across the range at nearly every point except near center. Granted, they could have tested a bad copy, but that just as well could be indicative of the lens regardless of copy ... I'd defer to someone with a copy of the lens for input that disagrees with the tests. However, the tests should still hold water in making a decision.

10-22 for crop....17-40 for FF

FastCougar wrote in post #13056383
I don't know ... take a look at at the top link again and you can clearly see fringing (chromatic aberration) on the Sigma across the range at nearly every point except near center.

I don't really see any CA worth mentioning there
In fact, the canon images look slightly more purple to me.

Sirrith wrote in post #13056675
I don't really see any CA worth mentioning there
In fact, the canon images look slightly more purple to me.

Wow, you are right ... I think the way the website is changing images is glitchy after checking the link again. I see the sigma is clearer and more crisp now, but before, when I made those comments, I was changing the lens settings (focal depth and f-stop) and what it was saying was the Sigma was horribly fringed ... as in extremely horrible (bright purple halos). However, after re-clicking the link now, those images are definitely not appearing as they were. I design web applications for a living and can only assume they have not accounting for browser caching properly. My bad ... or is it

Sirrith wrote in post #13056256
And canon won't really care, because the APS-C market isn't what the 17-40 was designed for. Its an UWA for FF, not a normal zoom for crop.

17-40 is designed as a UWA for ff, aps-c equivalent is 10-22. The two lens are designed for totally different purposes.

OP is really comparing apples with oranges.

kin2son wrote in post #13056793


17-40 is designed as a UWA for ff, aps-c equivalent is 10-22. The two lens are designed for totally different purposes.

OP is really comparing apples with oranges.

Where did I mention the 10-22 ?? I have a super sharp Sigma 10-20 and am not considering a UWA.......... If you read my origional post I specifically only mentioned 2 lens - the 17-40 and the 17-50.

Strangely I was working in a Council civic building today, and was asked by a photographer to sit in a chair so he could take some test shots in the lighting conditions.......... He was using a 7d with a 17-40. I only had 2 mins to chat to him, he LOVED the combo of those two. He called his workhorse, his favourite lens.

Ian, while I'm new to P.O.T.N. I've been a semi pro photographer for
over 30 years. I offer that to show that I'm serious about the craft and do my
research on gear.
I own the C. 17-40 and use it on a 7D as well as other bodies. The reason I bought
the 17-40L was quality construction, weather seal, and IQ. On the 7D you get the
sweet spot on this lens. On the Sigma, which I also have considered picking up, you get,
reach, OS and, IF, you get a quality lens, useable 2.8, no "sweet spot" as it's for APC sensors.
The problem I've run into with SIgma is what I call the Russian roulette factor, Will you get an excellent copy or wont you? Sure this can happen with any brand, but Sigma is known for it's
variability from copy to copy. Check user reviews on B&H. I look for Semi-Pro and Pro users.

I love the 17-40, but I will tell you that even though it's a short lens, I do miss the O.S.
I primarily do Landscape work, so 2.8 is not a primary concern, but image quality is. I also
work at high elevation, so weather seal is of paramount concern.

Check out lens reviews/tests on photozone.de I have used their input for many purchases.

Good luck. Also, Sigma Customer Service can be moody, depends on who you get to help you.
I have had some good luck with them and then not so much.