Shooting video with EM5: S-AF versus C-AF

Discussion in 'Olympus Cameras' started by Ionnas, Mar 9, 2014.

  1. Ionnas

    Ionnas New to Mu-43

    Mar 9, 2014
    Hello to everybody.
    I don't understand the difference between S-AF and C-AF by Shooting video with EM5 (in M-Modus). In both cases the camera tries to refocus when I come closer or I move it to a new object or I rezoom out / in.
    I always stop down the aperture and turn up the lights or ISO tot avoid the focus hunting. But it is still not clear which focus mode is better to use.

    My lens is an Olympus M.Zuiko Digital ED 14-150mm.

    Thank you
  2. popiT

    popiT Mu-43 Top Veteran

    Mar 20, 2014
    BayArea, CA
    Neither :smile: Use MF when shooting video and yes "Manually Focus" literately.
  3. Bif

    Bif Mu-43 Top Veteran

    May 28, 2012
    San Angelo TX
    Bruce Foreman
    S-AF is supposed to give ONE single autofocus operation per half shutter press. If you experience "focus hunting" as you change camera view in this mode, you must have focus tracking or C-AF set in some menu configuration. The Oly menus are "overdone" IMO, but I use the OMD E-M5 in video mode mainly for it's 5 axis IBIS.

    C-AF is supposed to attempt to function in the same manner as we were used to with video camcorders, but in actual practice I find it totally unreliable with much focus hunting as you move or the camera moves to change what the camera sees. This function is somewhat better on the GH3 but not enough to depend on.

    So manual focus is the way to go.

    More light might help, but turning up the ISO or closing down the aperture will have little effect. Your best solution is manual focus, yes this will have problems too as the subject moves around. Again the GH3 is a better performer in this respect as long as the background does not have enough contrast to cause constant focus "shifts" between subject and background.

    A rather ingenious solution is seen in the "Making Of Musgo" on vimeo. The camera operator (with GH2) is "tethered" to the subject with a line tied around their waists so the camera operator can maintain a constant distance while both are moving. Good for "waist up" closeups only, same was applied indoors where no movement was done so a constant "focus distance" could be maintained.
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