Auto focus questions (G7)

Discussion in 'Panasonic Cameras' started by btaylor, Sep 18, 2016.

  1. btaylor

    btaylor Mu-43 Regular

    48
    Sep 5, 2016
    Ben
    Hello,
    Couple of question regarding auto focus operation. I have the DMC-G7 (but the answer may be the same as for other models).

    1) Does/can the camera adjust the aperture depending on the size of the AF area? So, for example (in "P" mode) if I set the AF area to a fairly big area, and some parts of the subject in that area are further away than others, does it adjust the aperture so the depth of field is sufficient to make all parts of the subject in focus?
    If not, why are any of the AF areas other than 'pinpoint' any better than pinpoint, i.e. why would I not just use pinpoint all the time if I still have to be conscious of the aperture in order to make sure all the subject is in focus?

    2) Is there a quick way of 'resetting' the auto focus area? The quickest way to do it seems to press left, down, disp, set - which is four presses. Just wondering if there was a quicker way? Can't I tell it to 'forget' when it's turned off?
     
  2. stratokaster

    stratokaster Mu-43 All-Pro

    Jan 4, 2011
    Kyiv, Ukraine
    Pavel
    1) no, the camera will not adjust the aperture automatically, this is your prerogative as the photographer

    2) you can either assign a function button to quickly move the AF area (then you can always reset the focus area by pressing just two buttons), or you can use one of the custom modes — then the camera will always return to your saved settings after cycling the power.
     
  3. btaylor

    btaylor Mu-43 Regular

    48
    Sep 5, 2016
    Ben
    Ok, that works. Thanks.

    Another question if I may! Sort of following on from my previous thread about the difference between AFC and tracking (https://www.mu-43.com/posts/930036/), but:
    I've just been 'testing' AFC, or trying to. I was under the impression it maintained focus on a specific subject, let's say if I have it on centre pinpoint - it maintains focus on whatever is in the centre of the frame.
    So I was trying to test that to verify my understanding of how it works / that it does work, by putting the camera on the floor, putting one shoe about a metre from it and another shoe about 3 metres from it. I put it on AFC, get shoe 1 in the centre of the frame, focus on it. Shoe 1 is in focus, shoe 2 isn't. Fine so far. I then rotate the camera so that shoe 2 (further away) is now in the centre of the frame. I was expecting it to refocus on shoe 2, but it doesn't, it stays focused on the near one.
    This means it either doesn't work, or doesn't work how I understand it to - I suspect the latter. Does the subject have to move relative to the background? What simple test can I do to see the difference between AFC and AFS?
     
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  4. Duke Sweden

    Duke Sweden Mu-43 Regular

    66
    Aug 9, 2016
    Duke Sweden
    Thanks for doing the heavy lifting for me! ;-) I came here with the same "shoe" problem, only, with me, sometimes the camera does change its focus, other times it does nothing. I even have one clip that was just completely out of focus to begin with, and stepping into the frame didn't get it to change either. Frustrating since, with my eyesight, I can't tell if the camera is in focus or not when I stand far enough away to get into the frame. Also talking about a G7, btw.
     
  5. DanS

    DanS Mu-43 Veteran

    393
    Mar 8, 2016
    Central IL
    This will answer all your focus questions.

     
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  6. btaylor

    btaylor Mu-43 Regular

    48
    Sep 5, 2016
    Ben
    OK, I kept testing it until I narrowed down what it was that caused AFC to kick in. Apparently it's that the subject has to be moving.

    I did it with a cup that was placed stationary and it doesn't work, but when I was holding it, it uses AFC. Even though I was trying to hold the cup still, it's enough motion that it knows it should use AFC.
    I've also noticed that if you have it on AFC, focus on a 'still' subject, the AFC icon instantly changes to AFS. I guess this is desirable, because you're more likely to be wanting to do a focus-pan-recompose than you are to be actually expecting it to re-focus on something still.
     
  7. Duke Sweden

    Duke Sweden Mu-43 Regular

    66
    Aug 9, 2016
    Duke Sweden
    Thanks, btaylor, but I have footage of it working on stationery objects and not working on stationary objects, working on moving objects, and not working on moving objects. The battle rages on!!!
     
  8. Bif

    Bif Mu-43 Veteran

    380
    May 28, 2012
    San Angelo TX
    Bruce Foreman
    AFC has not been refined enough to work reliably on m4/3 gear. I've tried to use it in the past but there are just too many things that are problematic with it. Focus "pumping" is one, where the camera will suddenly decide to focus on what's in the background then jump back to the main subject. Changing lighting conditions (sun going behind a cloud etc.) and more.

    Duke, if you have to get out in front of the camera there is a better solution. A wireless remote shutter release, I use this one on my G7 and on my GH4:

    https://www.amazon.com/Oppilas-RW-2...&sr=8-1&keywords=wireless+remote+for+lumix+g7

    A half press on the remote button does an AFS operation, focusing the camera, completing the full press will take a still photo in one of the still modes or will start the video recording in motion picture mode (motion picture camera icon on the mode dial). A second full press stops the video recording. I recommend you be in Manual Exposure mode when doing this for video.

    I sometimes make instructional vids and have to get out in front of the camera to demo something.
     
    Last edited: Sep 23, 2016