How do I determine if I need to AF micro-adjust? 7D mk II issues

[FlyingSquirrel]

How do I determine if I need to use Canon's AF micro-adjustment feature? Is there an easy test? While I do not tend to blame equipment, and will admit photographer error is more often the issue, with my new 7D mark II, I am having issues with my 500 f4 (admittedly, I have not tested other lenses yet). I feel like things are soft more often than with my 7D v1; the new camera is focused in front of the subject a lot. It's entirely possible that I don't have enough experience yet with the camera, and need to experiment with more of the AF case settings. I have set it how I would expect it should be set, based on my good results with the original 7D. (with the v1 of the camera, I only had trouble in poor light or low contrast subjects - all black, all white, etc). Your thoughts?

[dje]

Matt a couple of things to consider :

Try using single centre point focus so that you can make sure your focus point is on the wanted subject.

Try a comparison between normal AF and AF in Live View mode. In Live View mode, you are using the main sensor rather than the separate AF focus sensors (which can potentially have a calibration issue and require the use of AF micro adjustment).

There are tests of course that can be used to test for front or back focus (eg using a chart at 45 deg to the camera) but the above checks are easier in the first instance.

Dave

[ajohnw]

The easiest and for that and other reasons the best way of checking AF is here

http://www.northlight-images.co.uk/a...djustment.html

It's very sensitive. I even managed to check the focus scale on a near fish eye lens.

John
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[ajohnw]

There are a couple of other points. I grew up on film and manual focus. In that world things are focused into rather than onto subjects to make best use of DOF. I have often notice that AF can have a tendency to focus onto things. One suggestion from some one else is to move forwards after the focus has locked - how far depends on the subject etc. Not possible in continuous AF and that is where i have noticed the effect most often.

If you want to use live view to check focus on something other than the test chart I posted a link to compare with magnified live view manually focused. In loose terms the magnification needs to be sufficient to make up for the difference in pixel counts between the view and the sensor. You can also use live view to test against contrast AF but it is still worth checking that with manual focus and magnified live view. If the mag is high enough you will see what is actually going onto the pixels. DOF at that level is very short.

John
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[Downrigger]

How do I determine if I need to use Canon's AF micro-adjustment feature?

My understanding is that microadjustment is generally not often important in real world use, but, that said, after spending what one does for decent glass it seems hard to ignore any steps that optimize (however infinitesimally) performance, and so I have done that.

Perhaps some sages can help with "when does it actually matter, if at all?", my assumption being maybe it matters a bit for wide open shooting.

My other question would be: Is the microfocus adjustment indifferent to focal length for zooms, or does it slide around a bit? If the latter, it's hard to argue one should get very worked up about adjusting with zoom lenses.