Each camera was tested with about a dozen lenses each, at different FLs and distances. The method was to carefully focus manually and then shoot many AF shots with the AF sensors on the same target. The AF results were compared to the MF results.
So, using AF, the Nikon D7000 had 35.2% sharp images, 40% acceptably sharp images and 24.8% "out of focus" images. Among the lenses used was the Nikkor VR 2.8 70-200 IIG ED, whose AF samples hardly ever reached the sharpness of the MF samples.
Other DSLRs using phase detection AF did similarly poorly. The only camera which did very well, (almost 99% at least "acceptably focused") used contrast detection AF, but I won't mention which as that company never built a film camera (I highly recommend looking up the test!).
These results fit my own extensive real life experience, using both MF & AF cameras of many brands. There are particular situations where AF can have a focusing advantage as well as an undoubted production advantage, but for most photographic uses, it does *not* result in more accurate focusing, even when the sensor does try to focus on the right spot.
Remember, in the Nikon example only 35.2% of the shots were as sharp as a carefully focused MF image.
People who get their "information" mainly by reading marketing brochures may disagree...
Funny how there doesn't appear to be a large number of historically widespread negative reports on Nikon or Canon AF accuracy that I'm aware of, nor do friends who've shot both brands professionally with film and digital SLRs complain of AF anomalies attributable to the equipment. Maybe you could show where and how both makers have disappointed consumers for years with sub-standard products?
Private opinions are one thing. It's the private "facts" that are misleading.
My newer 1 series Canons rarely miss focus.
Even in poorly lit conference/event halls.
The 1v is a bit better than the 1n.
The 1D2 rarely misses ever.
5D has issues but not nearly as bad as the rep it has.
Or if it isn't online, it doesn't exist according to you?
It's not about "anomalies", but about technological limits and about what gives more consistently accurate results. If your standards are low enough, you might not even notice a difference...
Ironically, I found the most consistent results with my Nikon AFD lenses, came with the older F90x body which I still have, but even that was not totally foolproof, in low light with open aperture I would use manual focus. However, it was when the news publication I used to work for changed over to digital, some years back that the real problems started. For some reason autofocus on Nikon's digital cameras (and I'm talking about the early D1x, D2x etc.) was always slower to lock on than on the F90x, and in some instances it just "hunted" all over the place. The worst thing was the unpredictability of it all. (and this wasn't the only bugbear with digital by a long way).... Yes you could say the later D3 is better in this respect, but in a climate of drastically falling fees etc., it just doesn't make sense to pour yet more thousands moneywise down the "digital dark hole", just to get something that should have worked properly in the first place.
However, since I quit the news business, the pressure to shoot digital is no longer there and i've returned to film cameras, to manual FM2n's. I find them more reliable as cameras and the manual lenses more solidly engineered. For someone brought up with manual cameras, I have no need of all the automated bits and pieces, particularly when they don't always work as they're supposed to, and the AF lenses are often too flimsy to last the course.
I've had great results with my autofocus lenses, but then again, I only have two: the 28-105 and the 24-50. Both of them focus extremely fast, but they don't have the weight and heft that the manual focus lenses have. I can't really tell a difference in quality between the two...I would be hard-pressed to tell you whether or not a negative came from the newer 24-50 lens set at 50mm on my F100, or my old 50mm f1.4 that stays on my '68 vintage F. I will say that the only lens I've had issues with (and needed repaired) was an old 55 Micro...but I'm also reasonably careful with my equipment, so it tends to last awhile. As far as overall speed is concerned, even a lightning-quick autofocus lens won't work as fast as a hyperfocal setting...and if I'm working with narrow lenses that don't really support a hyperfocal technique, I usually have all the time I need for focusing. Overall, though: no problems with the autofocus lenses...they work well for me.
Here is a reference in English to the Colorfoto article:
The Colorfoto tests are in German. Unless you can read German you're going to have a hard time understanding the methods used in the tests. Rol_Lei Nut reported with specificity their conclusions. Take them for what they are-results of tests. If you can't examine the tests themselves that doesn't make the test results useless. I take them as interesting information, and my not being able to read German does make me dependent on someone else telling me what criteria the conclusions were based on. Without knowing the magazine I am also dependent on someone else telling me if in general their tests are well done. Still, in a test of this sort, results should be straightforward, as they measure things which can be well quantified e.g., "focused/unfocused" and fairly well quantified e.g., "acceptable". Popular Photography magazine has also published tests which showed manual focusing to be superior overall, and showed a surprising degree of inaccuracy in AF. And no, I don't know what issue it was anymore.
My own limited experience with AF is that Nikon is equal to manual focusing in good light and does well in the EV 0 range if I find it an area with good contrast. My experience with Canon has not been so good. It seems like like a "good enough" approach is taken, and have had images which showed inexact focusing even in good light (defining it as no less than open shade on a sunny day). Pressing the button multiple times improved results. I never used a Canon in really dim light so I don't how it does. A problem with either was the tendency of multiple focusing points to mean a lot of hunting or selecting away from the subject. I had a greater problem with the Canon consistently wanting to pick nearer objects, even with the subject centered. This has held true with a 10D I used recently.
This is singular, anecdotal evidence and should be taken as such.
The dinky viewfinders of crop-sensor digitals do make accurate manual focusing harder, compared to 35mm.