Top critical review
One person found this helpful
I don't want to say it's bad glass, but it doesn't really shine in the ...
on 3 September 2017
If you are looking for optical quality, this is not your lens. I don't want to say it's bad glass, but it doesn't really shine in the optical section.
Corner sharpness is not very good at any aperture.
Color and contrast are not bad, nor remarkable either.
Distortions are heavy but not uneven, and easily correctable, as vignetting.
AF accuracy is soso.
Even using Live view contrast detect focusing, it's not as reliable as whatever "L"canon glass I've ever used,
especially in low light situations.
Let me say that I mostly use this lens for landscape photography, so this downside does not bother me too much.
It's especially difficult to get everything in focus all across the frame, especially if you have different focal planes. You'll need to be very cautious about the hiperfocal distance.
All of these things will make you take your time to use it properly at any given situation.
Also, consider that you'll have to get a special adaptor and holder if you want to use filters.
Now the good stuff.
Great focal range. If You like going really wide, you'll love it.
Value for money. If you can afford the canon 11 24, probably it's way better but remember it's 4 times more expensive.
Now let me add one consideration, since I've read some comments comparing this lens to the canon 17 40 and I disagree. I own both of these lenses, and have tried two different copies of the sigma. I think the canon is a better lens, optically, and I'll tell you why.
I have tested both lenses at 17, 21 and 24 mm. At 17mm, f/11,(f/14 for the sigma, as the canon is f/4 at 17 and the sigma f/5)
it's a tie; the canon being slightly better on one side, the sigma on the other. But extreme corners resolution is better on the canon, no matter what aperture you use. From 19mm onwards, the canon wins hands down, everywhere. The canon is an old design compared to the sigma, and it's not a very good lens regarding its sharpness, particularly in the corners, so this doesn't speak very well in favour of the sigma.
Of course, the canon can't go wider than 17mm. That's the huge advantage of the sigma, regardless of its sharpness.
And the main reason why I keep it.