Interview with dual diode sensor designers

[KeithB]

http://www.learn.usa.canon.com/resources/articles/2013/eos_70d_interview_with_developers.shtml

Here is an interview with the designers of the new sensor that has Phase-detection focus points over the whole sensor.

[KeithB]

I just read the article and it is interesting that this new system is not guaranteed to work with all EOS lenses, currently 103.

Also, is it going to have a standard AF system when you aren't using live view?

[Bob Atkins]

I listed the lenses with limited function in my 70D preview - http://www.bobatkins.com/photography/digital/canon_eos_70D.html. They're mostly old, discontinued, lenses and mostly inexpensive consumer zoom, though there are a few of the earlier "L" lenses in there too.

The 70D has conventional phase sensitive AF using the same AF hardware as the 7D. No work yet on the firmware though, so it's not yet known whether the 70D will have all the AF modes that the 7D has. The 7D uses two Digic 4 processors, while the 70D uses one Digic 5+.

[Frank Kolwicz]

This sounds like the camera body I wish was built 5 years ago: 1.6x magnification relative to full-frame cameras, useable resolution level, adjustable angle LCD and fast LiveView focus.

I'm primarily interested in bird photography and often have to try to focus on subjects that are small in the frame and small compared to the area of a single focus detector (either the whole bird is small or I want to focus on a head or an eye). With my existing 7d and 5dII, the smallest focus element is almost always much larger than my desired focus point and that often causes critical focus to be missed. It would be great if this new system with it's fine, pixel-level focus sensors, could be selected at that level or close to it - that would clinch a buy for me.

[Bob Atkins]

Despite the individual pixels each being capable of phase detection I don't think the AF zones will be any smaller than those of the 7D or 5D II. I'm sure the camera needs to average the phase detection signal over a large number of pixels to ensure the accuracy of the measurement. Also, it only works in Live View mode of course - fine if you're happy shooting in live view, but many people prefer to use direct viewing. In direct viewing the 70D seems to be using the 7D AF hardware.

Given that the phase sensitive system in Live View is 99% aimed at video shooters (by providing continuous AF in video mode), I don't think we'll see super small AF zones available. Even if it was aimed at still shooters too, I don't see much likelyhood of Canon offering a supersmall AF zone.

We're still waiting for 70D details of course. Until Canon publish (or someone leaks) the user manual we aren't going to know the real details of the AF system.

Then of course there's always the 7D MkII...