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Autofocus

The 5D Mark III comes with a new AF system that is, in terms of specification, very close to the flagship EOS 1D X. It comes with 61 points, 41 of which are cross-type points and, uniquely to this sensor, five of them are diagonally sensitive (for these double cross-type, imagine an X overlaid on a + shape).

When used with lenses with a maximum aperture of F5.6 or brighter, the 5D Mark III is unmatched in terms of the number of cross type points it offers (21). Use an F4 or brighter lens and the advantage becomes even greater, with the camera gaining another 20 cross-type points that are further out from the center of the frame (Nikon's system only features cross-type sensors near the middle of the frame). Fit an F2.8 or brighter lens and the five central double-cross-type sensors become available.

The 5D Mark III only loses out to the Nikon D4 and D800 when it comes to use with slower lenses or long lens/teleconverter combinations, in that its cross-type points can only be used with lenses that are F5.6 or brighter. Canon says there's a trade-off to be made and that its approach allows the sensor to be more accurate with the large aperture lenses it expects its customers to use, and allows the F4 cross-type sensors to be placed further towards the edge of the frame.

And, while the system doesn't have the 1D X's 100,000 pixel metering sensor, it still has a 63-point, color-aware metering sensor (a Foveon-esque two-layer affair), to help the camera track subjects.

F2.8 or brighter
F2.8–F4
F5.6 or brighter

The other key improvement is the simplification of the AF configuration. Previous high-end Canons have had very capable AF systems but have required fairly extensive training to correctly optimize them for the subject being shot. The 5D Mark III, like the 1D X, has a greatly simplified system for configuration, based on use-case presets.

AF configuration is complex compared to the 5D Mark II. But it's greatly simplified compared to the EOS-1D Mark IV, with a choice of 6 use-cases. The three parameters (tracking sensitivity, acceleration/deceleration tracking and willingness to switch AF points) can all be adjusted to more precisely tailor the presets to your favoured subject and shooting style.
The AF menu allows you to configure in detail precisely how you'd like the AF system to function, across fully five tabs of options.

Some of these have simply been ordered more coherently compared to where they were on the 5D Mark II, but there's a load of additional settings too, most of which are shared with the EOS-1D X.
You can choose which AF points you want the camera to use or allow you to select manually. The second setting - 'Only cross-type AF points' - takes into account the maximum aperture of the lens you're currently using.
AF microadjustment now allows you to program-in different settings for the two ends of a zoom. You can also enter an identification number for the specific the copy of the lens you're using.

We are no sports photographers but we can say that the simplified AF options are a great help when shooting moving subjects. We tested the EOS 5D Mark III's AF system with a 70-200mm F4L lens at an amateur soccer match, and even with our limited sports shooting skills got a very large proportion of usable shots. With the AF mode set to 'AI Servo' and the AF Case 4 'For subjects that accelerate or decelerate quickly' the camera locks onto a subject and tracks it reliably while shooting a burst.

The sample series below is representative for the kind of results we got. We locked focus on the player in the red shirt. The AF system tracks the subject but appears to get slightly confused when the subject is surrounded by other players. As a result in frames 5 and 6 the subject is very slightly soft, but even these shots would be usable on the web or at smaller formats. The AF also recovers quickly, with the subject in perfect focus again in the following shots.

Frame 1
Frame 2
Frame 3
Frame 4
Frame 5
Frame 6
Frame 7
Frame 8

In single AF mode the EOS 5D Mark III's AF performs very well, too, even in very low light, despite the lack of an AF-assist lamp. Rated down to EV-2, which is equivalent to moonlight, we've been constantly impressed by the ability of the 5D III's AF system to get solid focus in light where the 5D Mark II would have been completely unable to operate.

However, one thing to be aware of when shooting with wide apertures on a full-frame camera is the very little tolerance you have in terms of depth of field. When focusing on an image area outside the center of the frame it is advisable to move the AF point rather than using the center point and recompose. If you get consistent focus errors the camera's micro adjustment function can help, but in general it can still be a a good idea to focus bracket when shooting at longer focal lengths and wide apertures.

The camera's AF system works reliably and swiftly, even in low light. This picture was taken indoors at ISO 6400, 1/60 sec and F4.
And here's an even lower-light shot. Taken at ISO 25,600 at a shutter speed of 1/100sec and an aperture of f/5.6 the image in the viewfinder was barely bright enough for image composition yet the 5D III has captured a perfectly focussed, well-exposed image.

The contrast detect AF in Live View is still significantly slower than the standard phase-detect system. But this latest generation is now fast enough to make Live View a viable alternative for specialist applications such as macro or studio still life, or when the positioning of the camera makes it difficult to use the viewfinder.

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Comments

Total comments: 5
schutzaphoto
By schutzaphoto (3 weeks ago)

I work in Nyc as a fashion photographer and I have to say the the 5d series are the most used cameras out side of medium format cameras .Ive been shooting with the mark 3 for over a year after shooting with the mark 2 for 2 years great both great cameras. You can see the shots I've taken with it on my website www.brianschutzaphotography.com hope it helps!!

Comment edited 3 minutes after posting
1 upvote
Cyrus the Great
By Cyrus the Great (2 months ago)

Nikon D800 is clear winer over 5D iii in every things. Nikon has much sharper lens.
don't know why some people buy Canon???!!!!!

1 upvote
R D Carver
By R D Carver (2 months ago)

'Some people' buy Canon because they earn their living using a camera. Oh man, you should see those forests of white and red-ringed lenses in the pro pit at every major sporting, media and news event! 'Some people' are winning the major competitions, filling the fashion and nature magazines and filming box office busting movies with Canon. "Nikon has much sharper lens" Which lens exactly? Give a photographer a Canon 5D MKIII and an EF 70-200mm F/2.8 L IS II USM Lens and he can take on the world. Nikon is good, Canon is good why get tribal? it is so petty and amateur. At work I can pick up a Nikon/Sony D800 body or a Cannon 5D MKIII. I prefer the Cannon because I don't like the white balance on the Nikon. Others are happy to use the Nikon, but the die hard Nikon enthusiasts are disappointed that Sony make the sensors for Nikon. In comes Sony in comes the green tinged white balance.

2 upvotes
WillieG
By WillieG (1 month ago)

No cameras white balance is perfectly neutral. That's why we have the ability to manually change it on the camera and even fine tune on some of the higher end models. Nikon cameras do run slightly toward the cool side, but they can always be fine-tuned to be neutral in-camera. Canon cameras have always leaned towards the orange color tint. Luckily for Canon the end result is a slightly warmer image that many photographers like the looks of. Few pros would buy a camera that couldn't be made to produce true colors. And that forest of white lenses has been thinning out quite a bit since the advent of the Nikon D3. I'm one die-hard Nikon enthusiast who's ecstatic with Sony sensors. No other brand can even match their dynamic range.

Comment edited 6 minutes after posting
0 upvotes
mufflon
By mufflon (3 months ago)

thx for putting the Shadow noise test in your review. it was time to show that quite big difference.

0 upvotes
Total comments: 5