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GH4 video autofocus tracking

Discussion in 'This or That? (MFT only)' started by teddoman, Feb 3, 2015.

  1. teddoman

    teddoman Mu-43 Regular

    191
    Mar 22, 2013
    nyc
    Hoping someone here with a GH4 could comment on how useable video AF is for casual videos of people. Does DFD keep up pretty well? I found some youtube tests where it performed reasonably well against some competitors but it's hard to tell from such limited and controlled tests.

    GH4:

    https://www.youtube.com/watch?v=59ggE-fG46k

    GH4 vs 70D:

    https://www.youtube.com/watch?v=HDEIHDSj8gs (starting at 8:38)

    NX1 vs GH4:

    https://www.youtube.com/watch?v=0DigAgYD-QY

    Does GH4 identify and track subjects pretty well in a dynamic people scene (like kids milling about)? Can it handle kids moving around quickly and in and out of the frame? Does it guess who the subject might be reasonably well when there are lots of possible moving or stationary subjects? Does it get confused, or does it stick to something?

    Does it focus hunt to the point of being distracting, or does it manage to make a reasonable guess as to whom the subject is and stick to them?

    Are there any 1.4 or 1.8 reasonably wide lenses that are silent and optimized for video? Or would I have to use a 2.8 zoom?

    And does the GH4's ability to AF at -4 EV also apply to video? Thx for any answers.
     
  2. Lunatique

    Lunatique Mu-43 Regular

    97
    Sep 14, 2014
    Lincoln, CA
    I'm contemplating getting a GH4 to replace my E-M1, because I want the fully articulated screen and also the 4K video to create still photos from (so I don't have to decide whether to shoot stills or video during interesting moments). So I've been doing a lot of research on the AF tracking of the GH4 during video, and what I've learns is the following:

    It will track AF much better in 1080p--good enough that you really don't have to worry about it--especially after the latest firmware update, which addressed the AF tracking issue the GH4 had early on.


    In 4K, the AF tracking is much worse, even with the firmware update it is still problematic, often wandering to the background when there's a clear, well-lit foreground subject to focus on, regardless if the subject is relatively still or moving around a lot.


    One thing I've wondering about though, is since the GH4 allows touchscreen focusing during video recording, is it possible to "help out" the AF tracking a bit by touching where you want the camera to focus whenever it has a hard time finding the subject. This only helps when it can't find the subject, but it's not going to help when you need it to stay locked on the subject and not waver at all.

    For my needs, I'm currently not shooting anything mission critical, so I don't mind that it might not stay locked on the subject, but I DO want it to get right back to the subject if I touch-focus on the subject to help it get back on the tracking.

    Can you GH4 owners confirm this is possible? Or the touchscreen AF doesn't help the AF tracking and once it wanders off, no amount of touching where I want it to focus will help guide it back immediately?
     
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  3. DaveEP

    DaveEP Mu-43 Top Veteran

    683
    Sep 20, 2014
    York, UK
    The problem with touching the LCD is it forces it to focus there, which in theory is what you want, but it means it does it's hunt back and forth until it locks, which is worse than just tweaking the lens manually.

    The GH4 has become my default camera, leaving the C100 in the bag now. In fact, I just realised I haven't used it for months. Ouch.
     
  4. teddoman

    teddoman Mu-43 Regular

    191
    Mar 22, 2013
    nyc
    Disappointing to hear about your findings on 4K on the gh4. That would be part of what differentiates gh4 from my current gear to justify a purchase.
     
  5. dornblaser

    dornblaser Mu-43 Hall of Famer

    Aug 13, 2012
    Chicago-area
    David Dornblaser
    I don't think that it is a surprise that if you look at published videos that Olympus primes are being used a lot on the GH4, particularly the 12, 17, 25 & 45. Voigtlander also make makes fast, silent glass; although, not AF. As to AF with 4K, I have only shot 4K with MF. I don't see the target market for the GH4 being those who take videos of their kids milling around. Absolutely no offense meant. There are a small, but increasing number, of camcorders that shoot 4k that might be a better match. Sony comes immediately to mind.
     
  6. teddoman

    teddoman Mu-43 Regular

    191
    Mar 22, 2013
    nyc
    I think I read that Samsung etc are doing 4K to support their 4K TVs. Seems like it's only a matter of time for pro to trickle to amateur and then to prosumer. As a result, anything less than 1080p just seems weak, which is yesterday's 4K.

    In a way it may not matter who is being targeted anyway, the reality is the market is very competitive. Sony A7S and Samsung have full sensor readout and 4K. Samsung is putting pdaf tracking and full sensor 4K in a $800 nx500 kit. Choices are great right now and prosumers will select the best values for their own needs.

    Market moves so quickly. Who knew 4K would become prosumer so quickly. It was pro only when gh4 came out.
     
  7. dornblaser

    dornblaser Mu-43 Hall of Famer

    Aug 13, 2012
    Chicago-area
    David Dornblaser
    Yes, but for the current market I don't think that you are breaking it down finely enough and maybe projecting your video needs too much. I don't think the GH4 is right for you based on this short thread.
     
  8. teddoman

    teddoman Mu-43 Regular

    191
    Mar 22, 2013
    nyc
    A lot of cams are still based on traditional idea of manual focus for pro video. But autofocus in video is improving. I wonder if there will be a day when AF in video becomes as normal as it is for stills.
     
  9. DaveEP

    DaveEP Mu-43 Top Veteran

    683
    Sep 20, 2014
    York, UK
    Two things.....

    • The samsung cameras are currently a bit of a pain to work with because they are using h.265 (not h.264) as their codec - fine for playback on Samsung (and other) 4K TVs, but if you want to edit it you have to transcode in to something more suitable because almost no NLEs currently support h.265 natively. That will change of course, but you are going to need a beefy CPU / GPU to do it.

    • If you really want reliable, transparent auto focus on a camera then you need a camera that was built from the ground up to have it, not one that has it bolted on. Thats why camcorders are better than DSLR/Mirrorless at this time, they've had AF for video built in from the group up. http://www.panasonic.com/uk/consumer/cameras-camcorders/camcorders/hd-camcorders/hc-x1000e.html

    Sony also have some reasonable offerings now too.
     
  10. dornblaser

    dornblaser Mu-43 Hall of Famer

    Aug 13, 2012
    Chicago-area
    David Dornblaser
    I am sure that it will.