6D autofocus irregularity

[Bucksflyer]

I have a 6D plus 24-105

Last couple of weeks in P mode the camera does not focus and keeps hunting from sharp to blurry.

Anyone know the cause and a fix?

[Waddizzle]

Which version of the 24-105mm lens?  I can think of at least three versions.  What shooting mode, One Shot or AI Servo?

Does this only happen in P mode?  What happens in Green [A] mode?  It would be most peculiar for this to only happen in just one shooting mode, if the lens were at fault.

What are you aiming at?  Try it outside on a bright sunny day.  Aim at something a couple of car lengths away, like a fence, house, tree, cat, dog, etc.  Use One Shot focus mode.  The Green [A] mode forces the camera to One Shot mode.

If it still doesn’t lock focus.  Try a different lens.  Use the menu setting to reset the camera back to factory defaults.

[Bucksflyer]

It was happening in Green as well as P mode. The lens is 24-105mm F/4.0 USM IS

However, this morning I changed:

1) Auto Focus to Center

2) Shooting to single shot and,

3) Metertering to Center weighted

I tried taking some portraits as well as Flowers in Vase.

The Hunting seems to have gone (for the time being).

Regards

[ebiggs1]

"2) Shooting to single shot and,"  

Keep it there until you become more familiarized with how the 6D works.

[jrhoffman75]

In order to focus properly (assuming you are not closer to the subject than the lens's closest foucus distance) is sufficient light and contrast. As an extreme example, a lens will never autofocus on a white wall. Draw a big black "X" on the wall and it will, becasue it will see the contrast between the black and white.

In auto focus point mode the camera will focus on the closest object to the camera with sufficient contrast. So, if you are trying to photograpgh a bird on a tree branch and there are some branches betweeen you and the bird the camera will lock on to them.

Selecting center point focus will allow you to position the single focus point on your desired subject; but if its a single color vase without a design there may be insufficient contrast. In that case move the focus point so its on the edge of the vase; it should focus then. You can hold the shutter button down half-way and move the focus point back to where you want on the vase and take your photo. Thats called focus and re-compose; just be sure that the focus point and the final point are basically the same distance away from the camera.

[JohnLo]

Sorry. I do not know how to start a new topic.

I bought my 6D used off CL. It is in extremely clean condition with about 4500 shots. There is a Canon brand grip attached. It has a problem with autofocus. I use EF 16-35mm f4 IS and a 24-70mm f4 IS lenses. At random times when moving the camera around the lenses will start "hunting" even when I am not pressing the shutter button. Why is this happening? I have installed firmware 1.1.9. This does not happen with my EOS 1-Ds Mk III and the same lenses. The lenses do seem to operate properly when I operate the shutter button. This is happening in the one-shot mode. Suggestions?

[jrhoffman75]

Has grip perhaps loosened slightly so that electrical contact is being broken?

[jrhoffman75]

[JohnLo]

I removed the grip. The lens is still "hunting" with only the body.

[RobertTheFat]

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@JohnLo wrote:

I removed the grip. The lens is still "hunting" with only the body.

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Did you buy the camera recently? If so, have you ever reset it to factory settings? What you describe could conceivably be due to some form of back-button focus being set. (Note that turning on BB focus does not, in itself, preclude the AF function of the shutter button from operating normally.)

I assume that you've verified that it really is AF hunting and not the lenses' IS.