Those who read this blog will know I am a big fan of mirrorless cameras and believe that they will be the future for most photographers.

Mirrorless cameras such as Micro Four Thirds have several important advantages over current dSLRs:

• they can be made smaller as they do not need the mirror, nor the pentaprism
• they are quieter to shoot as there is no mirror bouncing around, and also have far less camera shake at high magnification photography
• the lenses can be redesigned with shorter sensor to lens flange distances making for simpler wide angle designs and smaller, lighter lenses
• the shorter sensor to lens mount flange distance allows a greater range of legacy lenses to be usable
• AF for relatively stationary subjects is extremely fast, accurate and one can even automatically AF on a given eye (using Olympus cameras) almost anywhere in the frame
• no need for AF microadjustment calibrations
• use of an electronic viewfinder instead of optical allows more information to be visible without taking your eye from the camera such as live histogram, etc., and allow live magnification with image stabilisation, as well as live boost of low light situations for improved visability (particularly handy for astrophotography and when using legacy lenses stopped down)
• the electronic viewfinders continue to improve in viewing quality and refresh rates

BUT the current mirrorless cameras have one major flaw – limited or no ability to AF on fast moving subjects, limited tracking AF capability and very slow AF when used with non-CDAF lenses.

Olympus in particular is working hard to develop new mirrorless cameras which address the above issues and also allow fast AF with Four Thirds lenses.

Of all the manufacturers, Canon appeared to have been twiddling their thumbs on this front, even their mirrorless camera – the EOS-M was not taken seriously given that it’s contrast detect AF was so slow compared with the competition, and no new competitive technology had been created since 2009 – 4 long years allowing Nikon to take the advantage in dSLR markets and Olympus, Panasonic and Sony to take the strong lead in the mirrorless sector.

Now, with their announcement of a revolutionary new “dual-pixel” sensor in their Canon EOS 70D dSLR which promises to not only provide contrast detect AF as with traditional mirrorless cameras but also the most capable and fast on-sensor phase detect AF system yet made. If their claims are true, one should be able to use most of the EF lenses and have fast AF with tracking and even face recognition with these lenses anywhere within 80% of the image area in Live View mode.

This is awesome news if the claims are proven and will again give Canon an edge, particularly when they introduce this technology in the mirrorless cameras.

BUT it may be a double-edge sword for Canon who have relied upon its dSLR sales to date.

If this sensor is as good as they state, I for one would want to be using the Live View Face Detect AF with my Canon EF 135mm f/2.0L lens for portraits as the shallow depth of field of this lens makes accurate AF on the eyes difficult with the current optical viewfinder.

Unfortunately with the 70D and other similar optical dSLRs, to use Live View means holding the camera away from your face and looking at the rear LCD screen. This is NOT a good method, particularly when using a telephoto lens when camera shake will potentially ruin your image, not to mention the ergonomics of holding a heavy lens in this manner.

If most people find that this new AF has substantial advantages over the old optical AF system as I suspect may be the case, then they would be best advised to buy a mirrorless version rather than a dSLR version, because there are now almost no reasons to have a mirror in your camera.

It will be very interesting to see how good this new AF system is, and, what will Olympus in partnership with Sony come up with in Micro Four Thirds cameras to compete with it.

Fascinating times.

Now if only Canon will make me a weatherproof, full frame mirrorless with an EVF built-in using such a sensor (even better if they add in-camera image stabilisation as Olympus do) !

Post Script:

It seems that reports on the pre-production model indicate that the AF is NOT as fast for static subjects compared with the current Micro Four Thirds cameras, and the Live View phase contrast is not as good as the optical phase contrast – the question will be – is it good enough for most of us, or just another compromise – time will tell, but at least the AF in movie mode seems to be nice and organic.