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DFD?

Discussion in 'Panasonic Cameras' started by PeeBee, Sep 27, 2016.

  1. PeeBee

    PeeBee Mu-43 Top Veteran

    660
    Sep 17, 2012
    UK
    Hey Folks,

    A quick question - What is your experience with DFD? Has it made much of an improvement? Ideally, I'm looking to get an improvement in S-AF locking on a moving subject and I'm wondering how much better a DFD model would be over my G5? My reference point is my 5 year old Canon Rebel (not exactly an AF monster by any means) which I'd like to replace with a newer M43 body (possibly a G80?) if I can get a somewhat comparable S-AF performance with moving subjects. As promising as the EM1 mk2 looks, I don't want to spend that kind of money at the moment (2 kids in higher education!) so if consumer M43 isn't quite there yet, I'll either hang on to the old rebel for a little longer or replace it with another Canon APS-C.

    Thanks!
     
  2. gryphon1911

    gryphon1911 Mu-43 Hall of Famer

    Mar 13, 2014
    Central Ohio, USA
    Andrew
    I believe you'll find that DFD or PDAF enabled sensors AF benefit is more to the C-AF needs.
     
  3. tkbslc

    tkbslc Mu-43 Hall of Famer

    S-AF on a moving subject is already a problematic exercise. You'll already be out of focus by the time the shutter trips because the subject has kept moving!

    What exactly are you trying to photograph?
     
  4. Danny_SWE

    Danny_SWE Mu-43 All-Pro

    Apr 30, 2013
    Sweden (Gothenburg)
    Maybe AFF would be good then, with a blistering fast focusing lens
     
  5. PeeBee

    PeeBee Mu-43 Top Veteran

    660
    Sep 17, 2012
    UK
    I rarely take my Rebel out of S-AF as it's better at S-AF than C-AF. Moving subjects are relatively easy with it, but I find it near impossible with my M43. Just last weekend I tried to shoot a plane moving fairly slowly across the sky. Using centre point S-AF on my EM10, and the centre point placed firmly over an area of good contrast, it couldn't lock. The Canon would have no problem. Yet on a static subject, my M43 would be quicker, especially my G5. There's plenty of great BIF shots on this forum done with M43, so it must be possible, but I can't seem to master it.

    The gumph I've read on DFD concentrates on it being faster than non DFD, but not in any specific mode. So my line of thinking is that if it's faster, there will be less movement between AF activation and lock. I'm just wondering of anyone has any real world experience to confirm that? Panamike for example is posting image after image in the Share Birds thread, captured with his GX8, so maybe DFD does help?

    And l read lots of posts from people that have more success with S-AF on moving subjects than C-AF, especially with M43 where the deeper DOF helps.

    S-AF on my 2011 Rebel.......

    IMG_0740 2.
     
  6. tkbslc

    tkbslc Mu-43 Hall of Famer

    Have you tried using a smaller focus square?
     
  7. PeeBee

    PeeBee Mu-43 Top Veteran

    660
    Sep 17, 2012
    UK
    I usually keep it at the smallest setting, but I've tried larger too.
     
  8. Hypilein

    Hypilein Mu-43 Veteran

    290
    Mar 18, 2015
    As you've already mentioned him maybe @panamike@panamike is willing to shed light on his technique?
     
  9. PeeBee

    PeeBee Mu-43 Top Veteran

    660
    Sep 17, 2012
    UK
    ^ He's already posted it in the Share Birds thread. S-AF, so the difference could be the hardware used (not ruling out better lenses of course)
     
  10. Giiba

    Giiba Something to someone somewhere

    273
    Aug 19, 2016
    Burnaby, BC
    I've been hunting the web for any sort of test comparing a DFD camera to anything. I'd really like to see a test comparing a DFD camera to an e-m1, can anyone link something?

    All I can find is explanations of what it is.
     
    • Agree Agree x 1
  11. Phocal

    Phocal Mu-43 Hall of Famer

    Jan 3, 2014
    Here are two videos that were before firmware 3.0 on the EM1. In the first he states the EM1 was better at CAF then the GH4 but the GH4 focused faster. They got a lot of blowback because they used the Panny 35-100 on both cameras and not the Oly 40-150 Pro on the Olympus. So in the 2nd video when they reviewed the two lenses against each other they tested focus speed of the two lenses and determined that there was really no difference in focus speed between the two cameras. This was before the EM1 firmware upgrades which greatly improved the EM1's CAF ability. I have not been able to find any kind of review of the EM1 after firmware 3.0 in respects to CAF performance vs Panasonic DFD.

    <iframe width="560" height="315" src="" frameborder="0" allowfullscreen></iframe>

    <iframe width="560" height="315" src="" frameborder="0" allowfullscreen></iframe>

    In his review of the Panny 100-400, Matt over at Mirrorlessons concluded the lens performed better at CAF when using the EM1 over the GX8 - The Panasonic 100-400mm f/4-6.3 Review - MirrorLessons

    Those are the only ones that I know of that compare the EM1 vs DFD. If there are more I look forward to someone pointing them out.
     
    • Appreciate Appreciate x 2
  12. Giiba

    Giiba Something to someone somewhere

    273
    Aug 19, 2016
    Burnaby, BC
    So in other words DFD is just marketing speak for CDAF to make it sound more advanced?

    I find the lack of testing of this feature suspicious. What would be most telling is a comparison between the gx8 and e-m5ii.
     
  13. Phocal

    Phocal Mu-43 Hall of Famer

    Jan 3, 2014
    Why do you say that? The EM5 is terrible at CAF, at least the GX8 has DFD........DFD is the technology that Panny is using for CAF over the more traditional PDAF. There is a huge difference between a camera with just CDAF and one with CDAF + DFD.
     
  14. ripleys baby

    ripleys baby Straw clutcher

    609
    Aug 10, 2011
    I've actually got a better keeper rate with my GX8 than i ever did with my Canon 7d.
    Admittedly this could be because of the greater dof of the GX8 or user error with the 7d.
    I'm much happier with the GX8 with moving subjects.
    26682022232_ae5ab77692_b. P1010065 by sucofni, on Flickr
     
    • Like Like x 1
    • Informative Informative x 1
  15. Turbofrog

    Turbofrog Mu-43 Hall of Famer

    Mar 21, 2014
    DFD uses CDAF, but it also uses a lot more information in the image to make it more decisive. CDAF can only confirm when something is in focus, which is why it hunts back and forth until it gets there. M4/3 cameras can do that hunting really, really quickly, especially in S-AF, to the point where it is essentially indiscernible, but they're still doing the basic process.

    Z_GH4_DFD-drawing.JPG
    As I understand it, the DFD algorithms in some ways try to achieve PDAF-like capabilities without using the dedicated hardware. By evaluating the character of the out-of-focus areas and how they change as the focus is racked, the camera can gain an understanding of how far away the subject is and whether it is in front of or behind the focal plane, so that it can be more decisive in the initial focus acquisition before it reverts to standard CDAF algorithms to fine tune.

    Most mirrorless cameras with PDAF still use CDAF for final focus confirmation (sometimes called Hybrid AF), though some Sony cameras will now use strictly PDAF depending on the mode, especially where super fast speed is the priority, as they deem it "good enough" if not perfect.
     
  16. PeeBee

    PeeBee Mu-43 Top Veteran

    660
    Sep 17, 2012
    UK
    Yes, from the explanation of how DFD works, it sounds promising, and it would be great if it could at least give a similar S-AF to my old Rebel, but I also agree that the lack of sound evidence on the interwebs does little to instil confidence. I think the problem with standard CDAF is that because the subject is moving, it can't establish a stable reference point on which to base it's contrast comparisons.
     
    Last edited: Sep 27, 2016
  17. Giiba

    Giiba Something to someone somewhere

    273
    Aug 19, 2016
    Burnaby, BC
    Uh..... the DFD line is how my camera focuses. It scans, overshoots, then goes back and forth a bit to confirm. I've yet to use a m4/3 camera (very few truthfully) that just hunts like that blue line.
     
    • Funny Funny x 1
  18. Giiba

    Giiba Something to someone somewhere

    273
    Aug 19, 2016
    Burnaby, BC
    So I've been reading academic articles on 'depth from defocus' and won't claim to understand it but I think I have some idea what's going on here.

    Theory holds that a minimun of two images are needed to do a calculation while most systems in use use three or more. So Panasonic's graph above is bullshit, but DFD will help in the case of c-af performance.

    The graph above claims the camera can estimate focal plane from a standstill (one image) which is wrong, but for a moving subject once an initial focus is achieved if the subject is moving suddenly the system has two (or more) images to calculate from which in turn would give subject distance change info which would be the beginings of predicting location at the next shutter release. So the more images the system checks the better it would be.

    I posit then that DFD is a benefit over traditional cdaf in c-af usage with a moving subject. So I woukd love to see some testing done betwren a DFD enabled combo and say and e-m5ii (or anything without DFD or pdaf) and/or an e-m1.
     
  19. jyc860923

    jyc860923 Mu-43 Hall of Famer

    Feb 28, 2012
    Shenyang, China
    贾一川
    What I'd like to know is how much caf performance would I lose if I use a non-DFD compatible lens, the 40-150 pro on a Panny body. If I have to guess, there's probably no practical difference because what Giiba said makes a lot of sense, DFD is comparing images, which doesn't require the lens "character" being recognised.
     
  20. barry13

    barry13 Super Moderator; Photon Wrangler

    Mar 7, 2014
    Southern California
    Barry
    Hi, Mat from Mirror Lessons tested the Pana 100-400mm on the GX8 and E-M1... for CAF on birds in flight he found it did better on the E-M1.
    Pana/Leica 100-400mm f/4-6.3 first impressions