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Question about focusing (video) with 25mm 1.4

Discussion in 'Native Lenses' started by loko12345, Dec 3, 2012.

  1. loko12345

    loko12345 Mu-43 Regular

    Jun 8, 2012
    Hi all,

    I have the 25mm 1.4 and have a question about focusing while shooting video.

    This is NOT my video, but it illustrates some of the issues I have been having: [ame=https://www.youtube.com/watch?v=PGFEi1qogUE]Panasonic Leica Summilux DG 25mm f1.4 Test Video - YouTube[/ame]

    I constantly have to half press the shutter to get the video in focus when I am moving or the subjects are moving. Is this normal given that this is a fixed prime lens? If not, how can I prevent this from happening?

    In short, I would like to shoot videos and keep things in focus without having to re-focus every few seconds if possible. Sort of like a constant auto focus. Would a zoom lens (like the kit lens) fix this issue?

    Any help would be appreciated.

  2. dav1dz

    dav1dz Mu-43 Top Veteran

    Nov 6, 2012
    No a zoom lens will not fix this.

    To prevent it from happening, you need to use a camera body that doesn't exist, or manually focus the lens. Sorry.
  3. loko12345

    loko12345 Mu-43 Regular

    Jun 8, 2012
    Okay, thanks. Just wanted to make sure I wasn't doing anything wrong as this is my first time using a "serious" camera.
  4. speedandstyle

    speedandstyle Mu-43 Hall of Famer

    What body are you using? What AF mode do you have it in? For video you need to use continuous AF or continuous AF with tracking{if you want it to stay on one subject}. However some bodies are more video oriented than others and thus do a better job of focusing. Keep in mind that professional video is usually shot using manual focus because even $10k video cameras can have AF issues!

    I do video as part of my job and have used some very nice cameras and they all can have trouble locking and keeping focus. The tool that allows easy and accurate focus while shooting video is called a "follow focus". On a big camera crew there is actually one guy who does nothing but focus, he is called a "focus puller".
  5. loko12345

    loko12345 Mu-43 Regular

    Jun 8, 2012
    Thanks for the reply. I am using the OMD EM5.
  6. ggibson

    ggibson Mu-43 Regular

    Jul 9, 2011
    Try AFS / Auto-Focus Single mode in video. The camera will only refocus when you half-press the shutter. In a video like this, there isn't much need to refocus anyways, since movement tends to leave the subject in the same focal plane.
  7. Steven

    Steven Mu-43 All-Pro

    May 25, 2012
    I know Panasonic GX1 has an option for continuous auto focus in video. To be honest, I usually turn it off because when I use it with 20mm lens it keeps hunting when in dark environments. Have not tried it elsewhere.
  8. dav1dz

    dav1dz Mu-43 Top Veteran

    Nov 6, 2012
    OM-D's default video setting is to use AF-C unless you changed it.

    I don't really use it much for video, there are very little controls during recording.

    It is more convenient for me to use my iPhone to record videos, 33mm equivalent perspective and I can share easily.
  9. speedandstyle

    speedandstyle Mu-43 Hall of Famer

    I am not much impressed with using a phone as a camera but you do make a good point. A smaller sensor means a deeper DOF and thus less AF hunting. The big deal about using DSLRs and MILCs for video is the DOF for artistic reasons, than and the wonderful and affordable lenses that are available. But all the guys doing video on larger sensor cameras use manual focus.
  10. speedandstyle

    speedandstyle Mu-43 Hall of Famer

    I have done this and it works. The E-M5 has a touch to focus screen, does that work in video mode? If so it is one way you could shift the focus when and where you want to during shooting.
  11. marcl

    marcl Mu-43 Regular

    Jul 8, 2012
    No, I don't believe the touchscreen works during filming to adjust focus on a different subject. Olympus really missed the mark on this one. The video from the OP is a perfect example of one that would benefit from that.

    For casual snapshot style video, it's best to shoot in Aperture priority, with a small aperture to maximize DOF. That'll help prevent some focus hunting in C-AF. (Note in this case, the smaller sensor 2x factor helps us!). I prefer to use S-AF so that I can refocus when I want with a half shutter press.

    Now, if you want to isolate your main subject against a blurry background, I thank the only way to go is to shoot in manual focus mode.

    The above are from my own experience. If anyone has criticisms or comments to had, I am a taker! Gotta get the videos of the little ones during the holidays right!!!
  12. speedandstyle

    speedandstyle Mu-43 Hall of Famer

    Too bad the touch focus doesn't work for video, yes Olympus did miss the mark if that is true.

    You are right about stopping down the aperture to gain DOF. In auto modes the camera will try to use as fast an aperture as it has so best to shoot in aperture priority or full manual mode. f5.6 would be a good point to start from.

    ADDED! In checking the specs of some Panasonic models it seems they can switch the focus point using the touch screen! The G3/5 and GH2/3 have this feature and perhaps other models do too.

    [ame="https://www.youtube.com/watch?v=Od8hTLTMHIA"]Panasonic GH2 touch screen rack focus - dSLR workflow - YouTube[/ame]
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