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.
The 20-megapixel resolution is Canon’s highest to date for an APS-C sensor, and the sensor design is radically different to anything we’ve seen before. Each pixel not only measures the intensity of light, but also the direction, with each one made up of two photodiodes facing left and right. This helps the sensor to perform phase-detect autofocus, determining not just whether the image is in focus, but also, if not, by how much. It means the lens can jump straight into focus rather than shuttle back and forth in search of a sharp picture.
Phase-detect autofocus is already available in all modern SLRs when using their viewfinders, but in most cases it’s disabled in live view mode. The 70D’s ability to perform phase-detect autofocus directly on the sensor makes it much faster than the 60D to focus in live view mode.
Our tests show that the Canon 70D is capable of capturing plenty of detail. However, even at the lowest sensitivity settings there’s a clear benefit to shooting raw files, since out of focus areas in JPEGs sometimes have a slightly watercolour appearance at 100% on-screen. In comparison, raw files look more natural.
Even images taken at ISO100 have a slight texture visible at 100%, but chroma noise (coloured speckling) isn’t a major issue throughout the native sensitivity range. As usual, however, in-camera noise reduction takes its toll on detail as sensitivity rises.
Raw files converted to TIFFs using the default settings in Digital Photo Professional look a little better than the JPEG files captured simultaneously, but we think it’s best to turn down the noise reduction a little as the raw files are processed, to reveal a bit more detail.
That said, there’s an impressive amount of detail visible in images captured at ISO12,800, and although there’s a fine-grained texture visible when images are sized to make A4 prints, it isn’t objectionable. If light levels permit, however, we’d recommend keeping below ISO6400 where possible.
The new autofocus technology is great news for photographers, but it’s potentially even more exciting for videographers. The 70D’s video autofocus was the most responsive we’ve ever seen from a large-sensor camera, adjusting in less than a second when we moved the autofocus point using the touchscreen. There was no sign of focus hunting, and face detection and subject tracking helped us follow moving subjects – although once again, it was a little unreliable.
Even so, when we tapped on a subject to focus on, more often than not, focus would remain locked as it moved nearer or further. We’ve always maintained that manual focus is the only way to achieve polished results, but for the first time, here’s a video autofocus system that we can envisage being used in professional productions. With a choice of 24, 25 or 30fps capture at 1080p, clips up to 30 minutes and an All-Intra mode that encodes at 75Mbit/s to avoid compression artefacts, it all looks pretty promising for serious video production.
Wi-Fi and connectivity
Wi-Fi is built in, with the same functions that we saw on the Canon EOS 6D. They include remote control via the accompanying iPhone and Android apps, with access to exposure settings and the ability to move the autofocus point using the smartphone or tablet’s touchscreen. While the 6D had to make do with lethargic live view autofocus, the 70D was much more responsive when shooting remotely. The app can also access the camera’s card to view full-screen previews with EXIF metadata, apply star ratings and instigate transfers.
We appreciate how both the remote shooting and image browsing modes are accessible without locking up the camera’s controls. Photos appeared in the app within two seconds of being captured, letting us use an iPad to review shots in more detail that the camera’s 3in screen allows. However, previews and transfers are limited to 2.5 megapixels, so it’s not so useful for checking focus. Enabling Wi-Fi disables the USB port and video capture, so a tablet can’t be used as a remote video monitor.
The iOS app worked fine in our tests but we could only connect our Nexus 4 smartphone via an existing network rather than make a direct connection. We’ve heard others have made direct connections with different handsets, but if this is an essential feature to you it might be worth popping along to a retailer and testing it with your own device.
Combining the usual array of physical controls with a touchscreen makes the Canon 70D quick and easy to use. While some photographers remain skeptical about the benefits of a touchscreen, we would urge them to try one of the modern systems, because they are far more responsive than some of the first touchscreens that appeared on compact cameras.
Canon has produced a very well rounded camera for enthusiast photographers. It has all the specifications that we expect, along with a few modern niceties in a body that feels well made and comfortable in the hand.
Even now, it should be seen as a decent alternative to the Nikon D7100 and D7200, and if you’re on a budget, a good alternative to the EOS 80D. All things considered, the Canon EOS 70D is a desirable camera that is capable of producing superb results.