Dpreview.During the early days of digital SLRs, Canon was pretty much the undisputed leader in CMOS image sensor technology. Almost every new EOS model came with an increase in resolution and high ISO range, and when the EOS 7D appeared in late 2009, the company had progressed from 3MP to 18MP, and ISO 1600 to ISO 12800, in just over nine years. But since then Canon's APS-C cameras have all sported variants on the same basic sensor design, to the extent that you could be forgiven for wondering what on earth their engineers were doing all day. Now we know.

The EOS 70D is a mid-range SLR for enthusiast photographers that from the outside looks like a sensible, indeed desirable upgrade to the EOS 60D. It borrows many of the best bits from Canon's existing SLRs, including the autofocus sensor from the EOS 7D, the fully articulated touchscreen from the EOS 700D (Rebel T5i), and built-in Wi-Fi from the EOS 6D. But on the inside it sports an entirely new sensor that is, potentially, revolutionary. It offers 20.2MP resolution, but uses a 'Dual Pixel CMOS AF' design in which every single pixel is split into two separately-readable photodiodes, facing left and right. This means that in principle they are all capable of phase detection autofocus in live view and movie mode.

On-chip phase detection is nothing new - we first saw it in the Fujifilm F300EXR back in 2010. Since then it's been adopted in one form or another by most manufacturers, with arguably its most successful implementation coming in Nikon's 1 System mirrorless models. But because until now it's used relatively few active pixels scattered sparsely across the sensor, it's had practical limitations, often only covering a restricted area of the frame and struggling once the light drops below outdoor daylight levels. Canon says that its Dual Pixel AF system, in contrast, works across an area 80% of the frame width and height, in light levels as low as 0 EV, and at apertures down to F11. This means it could well be the most capable live view autofocus system we've yet seen on any type of camera.

Canon 70DWe'll look at the technology behind the EOS 70D's live view AF in more detail later, but let's not forget that it has to work as a conventional SLR too. To this end it uses the same 19-point AF sensor as the EOS 7D for viewfinder shooting, but with slightly simplified control options in firmware. It can rattle shots off at 7fps for up to 65 frames in JPEG or 16 in Raw, and its standard ISO range covers 100-12800, with ISO 25600 as an expanded option. Image processing is via the DIGIC 5+ processor first seen in the EOS 5D Mark III.

In terms of control layout the EOS 70D is a logical evolution of the EOS 60D, adopting many of Canon's intervening updates and improvements. So it offers a full set of external controls to operate most key functions, and Canon's well-designed Quick Control screen to cover pretty much everything else. It also adopts the superb touchscreen interface that debuted on the EOS 650D (Rebel T4i), which we've found to be more useful than you might at first think. The 70D also regains an array of features that disappeared between the EOS 50D and 60D, such as AF microadjustment.
Canon EOS 70D key features

    20.2MP APS-C 'Dual Pixel CMOS AF' sensor
    DIGIC 5+ image processor
    ISO 100-12800 standard, 25600 expanded
    7fps continuous shooting, burst depth 65 JPEG / 16 Raw
    'Silent' shutter mode
    1080p30 video recording, stereo sound via external mic
    19-point AF system, all points cross-type, sensitive to -0.5 EV
    63-zone iFCL metering system
    98% viewfinder coverage, 0.95x magnification, switchable gridlines and electronic level display
    Fully-articulated touchscreen, 1040k dot 3" ClearView II LCD, 3:2 aspect ratio
    Single SD/SDHC/SDXC card slot
    Built-in Wi-Fi
    Single-axis electronic level
    Built-in flash works as off-camera remote flash controller
    AF microadjustment (can be set individually for up to 40 lenses, remembered by lens serial number)
    In-camera High Dynamic Range and Multiple Exposure modes (JPEG-only)
    'Creative Filter' image processing styles, previewed in live view

Key specs compared

In the table below we see how some of the EOS 70D's key specs measure up against its more expensive big brother, the EOS 7D, and its main rival, the Nikon D7100. What's interesting here is just how close the 70D is to the 7D in terms of spec - in much the same way as Nikon's D7000 made the D300S look almost redundant, it's quite difficult to see why most Canon users would now choose the top-end APS-C model.
Canon EOS 70D
Canon EOS 7D
Nikon D7100
 Effective Pixels      • 20.2 MP      • 18.0 MP      • 24.1 MP
 ISO Range      • 100-12800 standard
 • 25600 expanded      • 100-6400 standard
 • 12800 expanded      • 100-6400 standard
 • 50-25600 expanded
 No of AF points      • 19      • 19      • 51
 AF in live view      • Phase detection      • Contrast detection      • Contrast detection
 Screen      • 3.0" 3:2
 • 1,040,000 dots
 • Fully-articulated
 • Touch sensitive      • 3.0" 4:3
 • 920,000 dots
 • Fixed      • 3.2" 4:3
 • 1,228,800 dots
 • Fixed
 Viewfinder      • 98% coverage
 • 0.95x magnification      • 100% coverage
 • 1.0x magnification      • 100% coverage
 • 0.94x magnification
 Continuous drive      • 7 fps      • 8 fps      • 6 fps
 Storage      • SD/SDHC/SDXC      • Compact flash      • SD/SDHC/SDXC
 • 2 slots
 (inc batteries)      • 755g (1.7 lb)      • 860g (1.9 lb)      • 765g (1.7 lb)
 Dimensions      • 139 x 104 x 79 mm
   (5.5 x 4.1 x 3.1")      • 148 x 111 x 74 mm
   (5.8 x 4.4 x 2.9")      • 136 x 107 x 76 mm
   (5.4 x 4.2 x 3.0")
 Wi-Fi      •  Built-in      •  Optional      •  Optional


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