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CDAF vs PDAF for Baby photography

Discussion in 'This or That? (MFT only)' started by MingTyhMaa, Nov 1, 2012.

  1. MingTyhMaa

    MingTyhMaa Mu-43 Regular

    80
    Jul 20, 2012
    Lafayette, CA
    Ming-Tyh Maa
    I've had the GX1 with P45 for a 2 months now. I know there's certainly a learning curve for everything, but I'm finding that for taking shots of my baby, who of course bounces around unpredictably, I'm not achieving ideal sharpness in maybe 30% of my shots. I'm using face detection mode, AFS, assuming the milliseconds it take to catch focus should be fast enough.
    I guess the next logical step is to try it on AFC or AFF modes, and with quick AF on.
    Can someone confirm, on AFC or AFF, face detection, it will continuously autofocus WITHOUT me half pressing and holding the shutter right? So on AFF, there should be no need to keep quick AF on right?

    I don't remember having this high of a percentage of out of focus shots with a dslr on continuous AF,and I'm thinking of having a backup dslr. Unless someone tells me that with practice, I should be able to achieve the same keeper rate as a dslr.
    If someone does say this, can that person also confirm that the same equivalence is conferred in low light. Prevent me from spending more money!
     
  2. tuanies

    tuanies Mu-43 Veteran

    227
    Jun 13, 2011
    Graham, WA
    Tuan Huynh
    I used to use C-AF and constantly had blurry shots. Use standard AF with spot focus for better accuracy. Use the touch focus to zone into your ideal area.
     
  3. elavon

    elavon Mu-43 All-Pro

    Sep 1, 2012
    Tel Aviv Israel
    Ehud
    Another technique is to use manual focus.
    Pre focus to a certain distance and when the kid "bounce in" to that distance take the picture. To improve this technique you can in good light set an higher F-stop and get larger DOF.
     
  4. rhoydotp

    rhoydotp Mu-43 Top Veteran

    609
    Aug 5, 2012
    Toronto, Ont
    rpamparo
    i use the single-AF on my GX1, I found that any of the other mode (except manual) doesn't work well with fast-moving kids (i have 2 kids). from what I read, P45 focuses fast-enough anyway, I'm using the "dreaded" P20 and I can get good photos with this technique. There's a lot of talk here regarding the CAF on m43 compared to DSLRs that gets into the technical mumbo-jumbo :smile:

    about the low-light, i know some people here will cringe & disagree: use a flash to stop the motion. unless the baby is static, there's no way to do it unless you push your ISO very very high.
     
  5. tuanies

    tuanies Mu-43 Veteran

    227
    Jun 13, 2011
    Graham, WA
    Tuan Huynh
    I upgraded from the P20 to the PL25 just for faster low-light focusing. I have never fired off my flash. I'd rather take the ISO hit (up to 1600 typically, 3200 in a pinch) and just post process the RAWs in Lightroom. Also wide open at F/1.4 helps too :D.
     
  6. jyc860923

    jyc860923 Mu-43 Hall of Famer

    Feb 28, 2012
    Shenyang, China
    贾一川
    the quick AF helps only in good light and it's slow only to get a general idea of the scene IMO, helps with the capture somehow so I leave it on, but I don't think AFC works in such situations because on my GF3 the AFC is just hunting around and you'll end up getting a not so sharp yet not completely blurred image, want to know AFF too if you could try it, there's no AFF option on GF3 so couldn't help.
     
  7. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    The Leica 45mm Macro-Elmarit is a macro lens and will not focus quickly. Macro lenses are not made to focus quickly, in auto or manual. They are made to focus PRECISELY while taking your time. If you want quick AF, get a portrait lens.

    Were you also using a Macro lens on your DSLRs for comparison?

    As far as the need to half-press the shutter, I can't help you... I don't use those kind of "auto everything" methods. But there again, is another place where you are adding massive focus time. Try using single point-AF instead, and see how much faster it can be. Again, same on PDAF as with CDAF.

    In short, it doesn't sound like your problem has anything to do with CDAF vs PDAF as your title suggests, but with a myriad of other factors. Modern CDAF is now actually faster and more accurate than PDAF generally.

    Then there's also a chance that you're mistaking motion blur for mis-focus, with incorrect settings... there's just so many possibilities. Maybe post up some specific examples.
     
  8. MingTyhMaa

    MingTyhMaa Mu-43 Regular

    80
    Jul 20, 2012
    Lafayette, CA
    Ming-Tyh Maa
    Thanks for the input everyone. When I started the post, in the back of my mind, I was thinking the major problem was probably low light, as I'm shooting indoors, in which case, every camera autofocus will suffer a little no matter what.

    I'll spend some deliberate time on spot focus. Secondly, I think I'm going to just add more continuous light to the room, so I can get my shutter speed up. It's kind of interesting that the larger DOF per aperature is actually going to help me get things in focus.

    The P45 has a focus limit switch when one is not shooting macro, which I use. It seems relatively fast, though I have not used the O45.

    Good to hear that CDAF is faster and more accurate than PDAF. I think that's what I needed to hear.
     
  9. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    Yup, as you say no camera AF's well in low light. In fact, what you'll actually notice is that PDAF makes a lot of misfocus. It'll claim a lock many times when it has nothing. CDAF is just as slow, but is more accurate in that way.

    However, in actuality you should never have to get to that point of frustration with low-light Autofocus. Your eyes are so much more accurate in the dark, especially after your eyes have naturally adjusted to the light. Long before you start getting frustrated by AF, you should have switched over to turning the focus ring. You will save yourself tons of headache simply by reaching for the lens and turning the ring when the light gets low. I never understood why my peers would stand there cursing at their cameras after boasting about their DSLR's low-light AF capabilities, when all they had to do is turn the focus ring to get the shot. It's better to know your camera than to blindly rely on it.

    If you can add light though, that's the best. Always shoot with proper lighting wherever you can. An LED video light array on a bracket can also be a useful asset to low-light focus, whether using manual or auto.
     
  10. MingTyhMaa

    MingTyhMaa Mu-43 Regular

    80
    Jul 20, 2012
    Lafayette, CA
    Ming-Tyh Maa
    I respect the manual focusers, and i certainly do so with macro, but I feel like this is impossible with a newborn, who irratically moves in all 4 directions several times a second.

    More LED panels a comin!
     
  11. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    Not impossible, you just need to know the techniques to deal with various situations. :) I shoot manual with much more fast-paced action than that.

    However, more LED panels will do the trick for you so there's no need to learn something new. You've got the right idea. :D
     
  12. MingTyhMaa

    MingTyhMaa Mu-43 Regular

    80
    Jul 20, 2012
    Lafayette, CA
    Ming-Tyh Maa
    Ok, more practice.
     
  13. Amin Sabet

    Amin Sabet Administrator

    Apr 10, 2009
    Boston, MA (USA)
    If you think a two-month-old moves quickly and unpredictably, you're really in for it :). Have you tried touch autofocus? Helps cut down on time between focus and shutter release.

    Sent from my Galaxy Nexus using Mu-43 App
     
  14. rhoydotp

    rhoydotp Mu-43 Top Veteran

    609
    Aug 5, 2012
    Toronto, Ont
    rpamparo
    haha! no kidding!

    i love taking photos of newborn, they're a lot more "predictable" than a 2-year-old :smile:
     
  15. spatulaboy

    spatulaboy I'm not really here

    Jul 13, 2011
    North Carolina
    Vin
    How fast were the shutter speeds you were shooting? Like someone mentioned earlier, a lot of people mistake motion blur for missed focus while shooting indoors.

    If you do a lot of indoor portraits you really should think about investing in a flash and learning flash photography.

    Also, take a look at this thread: https://www.mu-43.com/f57/couple-shots-my-daughter-some-24035/
    He seems to be doing something right. :smile: