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| Re: Why Do Canon Lenses Score so Low? |
I just typed some comments on the sigma 24-105, parts of which have some relevance to your question, a quick cut and paste:
Count me super dubious of DxO when it comes to lenses.
First, why do they rank lenses based solely upon best aperture and focal length, what sense is there in that?
Second, since they seem to rate so many zooms best at wide open, like, just for starters here, they claim the 24-70 f/4 IS does best at 24mm and f/4? What are they measuring like the 4 center most pixels in the frame? Because I know that none of the lenses they'ved claimed best at wide open have done so for me in my tests or real world or on basically any other test site.
And they have so many weird results like: That the 16-35 II has the crispest edges on FF at f/2.8. That the 70-200 2.8 IS II is the worst performer at 200mm f/2.8 of all the 70-200 f/2.8 lenses. That the 70-300 non-IS has better 300mm than the 300 f/4L and 70-300L. And so on.
In fact they claim that every single one of those zooms perform the very best at wide open.
That seems impossible, so maybe for their overall score they simple try to find where each zoom does best at wide open and don't count anything closed down?
But how does that make any sense at all?
Their overall sensor scores were slightly dubious, but their overall lens scores are utterly absurd. Ranking lenses by the spot they are sharpest at wide open and ignore every single other aspect? it doesn't even begin to make any sense. What if one lens happens to do well wide open at one extreme but does barely better stopped down and stinks over the entire rest of the range? Who cares, rank it #1.
I'll also note that you can get the canon 24-70 f/4 IS from Adorama at the moment (after mail in rebate) for the exact same price as this Sigma and the Canon uses less expensive filters and is oodles smaller and lighter.
Also note, that in their best wide open test, the new tamron and new canon lenses do best at 24mm, which was always the real catch when it came to these lenses on FF, THAT was the trickiest part of the focal range while the sigma does not, according to their tests at least, do best at 24mm, but at 35mm (as with the 24-105L) where it has always been easier to find somewhat better performance at FF.
The real trick was always to find something that could handle 24mm crisp edge to edge on FF for landscaps. All the old standard zooms and even some of the old regular primes struggled a bit with that at 24mm on FF. The magic of the new tamron and new canons is that they finally deliver improved 24mm performance on FF in a zoom (or even in a lens just regardless).
So they can have a lens do best wide open at the easiest spot to do well and perhaps even stink everywhere else or perhaps at the focal lengths you care much more about or apertures you care more about and yet it might be ranked dozens of lenses higher than some other lens that might do better at a tricky focal length, etc. etc.