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GX7 Back-button Focus: Lock Focus, Release Back Button, and Maintain Focus Possible?

Discussion in 'Panasonic Cameras' started by Mohun, Jun 8, 2014.

  1. Mohun

    Mohun Mu-43 Regular

    Sep 19, 2012
    I’m afraid I’m going to belabor a point that I've been exploring as I contemplate the choice between a GX7 and the Olympus E-M1, but I will, i.e., as to the so-called (in DSLR lingo) "AF-on" or back-button focusing. As I read he knowledgeable responses from folks in the Olympus forum section of M43, it appears that AF-on focusing, functionally similar to that found in all of the advanced Nikon DSLRs, can be set up on the E-M1 with a bit a bit of somewhat complex maneuvering through the E-M1 menus. AF-on focusing as I have and do experience it in my Nikons makes it possible, given the appropriate menu settings, to 1) press either a dedicated AF-on button (in the Nikons and, by the way, in the Panasonic GX1 where that function can be assigned to the AEL/AEF button at the middle of the upper back of the body just below the top deck), lock focus and let that button go--for still subjects--or continue to hold down the button for subjects that are likely to move (commonly called AF-s and AF-c, or, sometimes, S-AF and C-AF, respectively in the autofocus world), and 2) squeeze the shutter release button (no half-press required) to execute the photograph.

    The primary issue for me with the GX7 is what I read in the GX7 user's manual on page 48, to wit:

    “…Fixing the Focus and the Exposure (AF/AE Lock)
    Applicable modes:
    This is useful when you want to take a picture of a subject outside the AF area or the
    contrast is too strong and you cannot achieve appropriate exposure.
    1 Align the screen with the subject.
    2 Press and hold [AF/AE LOCK] to fix the focus or exposure.
    • If you release [AF/AE LOCK], AF/AE Lock is canceled.
    • Only the exposure is locked in the default setting.
    3 While pressing [AF/AE LOCK], move the
    camera as you compose the picture and then
    press shutter button fully.
    A AE Lock indication
    • When [AE LOCK] is set, after pressing the shutter button halfway to focus, press the
    shutter button fully…”

    This appears to indicate that the button must be held down to keep focus locked, unlike the provisions in the other camera bodies that will permit releasing the button once focus is achieved (for still subjects) allowing a bit of leisure for the photographer to perfect the final framing and thoughtfully press the shutter release in one smooth motion.

    Am I mis-reading he GX7 manual on this score?

    And on a much more minor point (I hope) re the AEF/AFL button, does anyone think that that button protrudes just a litttle too little from the focus selector lever surrounding it. It seems to me from jut a few too few moments of handling that it might be difficult in some circumstances to get a good, solid push on the button, unlike most such buttons on a few other camera bodies where those buttons are not surrounded by another ring?
  2. j3t

    j3t New to Mu-43

    Jun 8, 2014
    Yes, it's possible

    You can do it. Getting the behavior requires changing a few custom settings (as it does on Canon bodies too - not sure about Nikon).

    Set AF/AE Lock to AF Lock or AF On.
    Press the button to achieve focus. With AF Lock you can then release the button to recompose and shoot. With AF On and AFF or AFC enabled you can hold the button to keep focus on moving subjects.

    Set Quick AF to off.
    This setting continually refocuses while you have nothing pressed as long as the camera is awake.

    Set Shutter AF to off
    This setting disables re-focus on half-press.

    I also like it with Eye Sensor AF set to off (so that the EVF eye sensor doesn't trigger AF), and Focus/Release Priority set to Release so that the camera will shoot a frame even if it thinks there is no focus. This is for focus+recompose situations. If you shoot in S A you may want the AF/AE lock to also lock exposure. I shoot in M, so I'm not sure how that works exactly.

    I'm pretty new to Panasonic bodies, but this combo works for me on a GX7 and GH4. If anyone else has additional options they set when using rear-button focus please share. There are probably options I'm missing.
    • Like Like x 1
  3. gugarci

    gugarci Mu-43 Veteran

    Jul 8, 2012
    Lyndhurst, NJ
    Here's how I have my GX7 set up for back focusing.
    I have my camera set up to use the function 1 button for the AF on, and have the AF/AE lock button for AE lock only. The reason I set up my camera to use function 1 is because my thumb rest over that button without stretching. However most people use the AF/AE lock button for back focusing. With my set up I can do back focusing which lock the focus when you remove your finger, and If I need to I can also lock the exposure separately before I release shutter.

    I have also have quick AF to off. the shutter AF to off, but I have the eye sensor AF set to on. I like having the eye sensor AF on because it speeds up the AF process for those times I need use the EVF for quick photo.
  4. T N Args

    T N Args Agent Photocateur

    Dec 3, 2013
    Adelaide, Australia
    call me Arg
    Yes. You have the option.

    "Maintaining/not maintaining the lock when [AF/AE LOCK] is released
    [MENU] > [Custom]>[AF/AE Lock Hold]>[ON]/[OFF]
  5. Mohun

    Mohun Mu-43 Regular

    Sep 19, 2012
    T N Args,
    Based on your quote of my posting "...This appears to indicate that the button must be held down to keep focus locked, am I misreading the GX7 manual on this score?..."

    and your answer:"Yes. You have the option...",

    What are my options? Are they 1) to hold down the button and continue focusing, 2) to hold down the button and continue focusing until I release the button, thus fixing focus, or 3) simply press the button and fix focus.

    Or are 2) and 3) exactly the same, unlike the Nikons, where it is possible to simply and clearly just press the button in one motion an achieve focus without having to "feel" when to release the button, i.e., one press is sufficient and release and timing thereof is irrelevant?
  6. Bif

    Bif Mu-43 Top Veteran

    May 28, 2012
    San Angelo TX
    Bruce Foreman

    On my GX7, GH3, and GH4 I have the AE/AF button assigned to AF LOCK. In the menus I have MF+ASSIST set to on, Focus mode to SAF+MF, and MF ASSIST set so the focusing ring on the lens is used.

    I leave SHUTTER AF set to ON.

    This way I can use the half press on the shutter release to autofocus quickly if needed. But one press on the AE/AF button does a single SAF operation and locks focus. ALSO SWITCHES TO MF! So I can "touch up" focus manually with the focus ring, magnified assist "kicks in" and I can "nail" focus accurately in the EVF. Or focus (manually) on something else if desired. While this focus LOCK and MF mode LOCK is in effect the shutter half press AF is disabled. Instead a half press of the shutter clears the magnified view back to normal EVF/LCD view.

    Full press on the shutter takes a still or starts video recording depending on mode you have set. MF mode remains in effect until you clear it by a second press on the AE/AF button which returns AF to default half press on the shutter.

    This gives me the best of both AF and MF worlds, and it works beautifully on all 3 cameras listed above. I also had it setup this way on my GX1 before I gave that camera to my grandson.
  7. gugarci

    gugarci Mu-43 Veteran

    Jul 8, 2012
    Lyndhurst, NJ
    Yes you are misreading it. Regardless of which button you use for back focusing it only focuses when the button is being pressed. The minute it lock focus and you let go of the button, it will not try to focus again till you pressed the button. You can also use back focusing for continuous AF. Check out the video below.
    • Like Like x 2
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