Inconsistent focus with 70D

[paulbpilot]

I'm struggling with gettng consisten focus results with my 70D. I can take two shots, one auto-focused right atfter the other, restablishing focus for each, and get very different focus results.

The setup:

Mode: AV

Lens: New Canon 70-20 mm 2.8 IS USM, zoomed to max

ISO: Auto

Style: Standard or Auto

Single Shot

Single point focus

Shooting across my back yard, approx 75 ft at woodend fence that contains lots of grain, and high contrast weathering. I can take on shot, handheld, refocus on another object, come back to the exact same spot on the fence, re-foucs and shot. One pic will be tack sharp on close inspection (fine grain in the wood is crisp) the other will have all the wood grain blured out with no definition. What the heck is going on?

[Ifly1956]

The 70d will allow you to display the focus points the camera used when you view the pictures with the cannon software. Turn this option on, and retry your tests. If the focus points are not the same, you really are not shooting the same picture each time, as the camera is focusing on different points.

This also lets your see the focus point, enlarge the picture, and see if that spot is tack sharp. This will let you know if it's the camera or the lens.

[Duped]

I have this problem too. Canon EOS 70D. 50 mm f1.8 II lens. When I take two same shots (on a tripod, exact same distance (7 feet, camera on two-second shutter delay, with on camera manual flash set at minimum power, at f1.8, ISO 100, shutter set at 1/250s) of a plastic container with printed markings which I use as basis for gauging sharpness, one image would be tack sharp while one would be blurry. Did this test repeatedly. My 70D is a lemon. Dreading the day too that it would for no reaon, suddenly die. Regretting buying the 70D. Regretting buying Canon. I got my 70D for its auto focus while shooting video. And I love it, except for these reasons.

[Waddizzle]

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@Duped wrote:

I have this problem too. Canon EOS 70D. 50 mm f1.8 II lens. When I take two same shots (on a tripod, exact same distance (7 feet, camera on two-second shutter delay, with on camera manual flash set at minimum power, at f1.8, ISO 100, shutter set at 1/250s) of a plastic container with printed markings which I use as basis for gauging sharpness, one image would be tack sharp while one would be blurry. Did this test repeatedly. My 70D is a lemon. Dreading the day too that it would for no reaon, suddenly die. Regretting buying the 70D. Regretting buying Canon. I got my 70D for its auto focus while shooting video. And I love it, except for these reasons.

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Can you tell me which AF focus point the camera is using?  If not, then you are most likely the problem, not the camera.   If you are allowing the camera to select an AF point for you when you shoot still photos, then that is the problem.  The camera will look for the nearest object to the camera and focus on that.

Learn how to select focus points.  My advice is set the camera to always use the center AF point.  I suggest using One Shot mode, too.  Your lens is not the best Canon makes.  In fact, it is one of the cheapest, and consistent, repeatable focus is not one of its' strong points. 

If you are using a tripod with a two second delay, then how are activating the shutter?  If you can afford the time for a two second delay, then I suggest that you manually focus the lens, using Live View to magnify the subject.

[ebiggs1]

" I got my 70D for its auto focus while shooting video."

You need to cal one of the 'friendly' Canon Support people.  You are doing something wrong and they can tell you exactly what.