Canon's 70D DSLR Introduces New Video-Centric Sensor

By Norman Chan

An on-chip AF system allows faster and more accurate auto-focusing when shooting video or photos in Live View.

When it comes to buying a DSLR, there a few major considerations that new shoppers should evaluate before going down the path of one specific manufacturer or product line. For DSLRs (meaning you're not considering buying a compact mirrorless camera), those major considerations include sensor size, low light sensitivity, and auto-focus speed/accuracy. Canon's newest 70D DSLR addresses the last attribute, with an emphasis on shooting video. The 70D, which comes three years after the announcement of the mild-mannered 60D, marks the first time in a long time that Canon has heavily updated its APS-C sensor. Its standard specs aren't very noteworthy: 20.2MP APS-C sensor, ISO from 100-12800, 7fps, 3" tilting touchscreen, 1/8000sec max shutter speed, built-in wi-fi. What is notable is the new autofocus system built into the sensor, called Dual-Pixel AF.

If you recall one advantage that DSLRs have over mirrorless cameras is their faster and more accurate phase-detect autofocus system. Mirrorless cameras use a contrast detect system that analyzes the edges of images to determine focus points (which also allows them to do focus peaking in LCD viewfinding). The downside of a phase-detect system [in previous DSLRs] is that it doesn't work well with a DSLR's pentaprism mirror. The mirror has to be flipped down for the camera to focus, which means you can't do immediate autofocusing when the mirror is up--for live view shooting or video shooting. Sony's one-way fixed mirror design in its SLT cameras bypasses this, but you compromise light quality by capturing images through that special mirror. In Canon's 70D, the new Dual-Pixel AF sensor has phase-detect AF built-in, meaning that it can focus while the mirror is flipped up. For non live-view photographs (using a flipping mirror), the 70D can use both the new sensor-based AF system and a traditional 19-point (all cross-type) AF system concurrently.

The 70D will ship in August for $1200 (body only) and $1350 with an EF-S 18-55mm f/3.5-5.6 IS STM lens.

So here's how Canon's DSLRs currently break down. If you're just a beginner and want a DSLR form-factor, get the T4i (skip the T5i). If you want something more advanced but don't want to spend $2000 dollars, you'll want to see how the 70D compares with the popular 7D. Both will likely be great for video, and I wouldn't be surprised if we saw a 7D Mark II by the end of this year. If you want to go full-frame, you know what I'm biased toward--the Canon 6D.