How autofocus often works.

Discussion in 'Open Gear Talk' started by Boid, Jan 11, 2012.

  1. Boid

    Boid SC All-Pro

    Dec 15, 2011
    Bangalore, India
    Rajiv
    • Like Like x 6
  2. Streetshooter

    Streetshooter Administrator Emeritus

    Jul 12, 2010
    Philly, Pa
    Thanks, interesting read.
    Don
     
  3. stillshunter

    stillshunter Super Moderator Emeritus

    Nov 5, 2010
    Down Under
    Mark
    Good one Boid. Mate thanks for keeping us all in mind. :thumbup:
     
  4. Brian

    Brian SC Top Veteran

    638
    Jul 7, 2010
    I have some of the 1970s Photography magazines that explained autofocus. Nikon had a contrast-detection lens for the Nikon F, "almost released". I have a 1983 Nikon F3AF that uses phase-detection.

    I still think the Polaroid SONAR system is the best.
     
  5. Luckypenguin

    Luckypenguin SC Hall of Famer

    Dec 24, 2010
    Brisbane, Australia
    Nic
    The great thing about CDAF is that when it gets it wrong, it usually gets it totally wrong. When PDAF gets it wrong, it gets it a tiny bit wrong and unless you review immediately you may not realise until it's too late. I'd relate the story of trying to get the in-camera focus micro-adjustment sorted on a Sigma 30/1.4, a Canon 50/1.4, and a Canon 100/2, or knowing that the same lenses may be virtually unusable at larger apertures on a camera body without micro-adjustment, but I don't think that swearing is allowed on this board.
     
    • Like Like x 1
  6. Brian

    Brian SC Top Veteran

    638
    Jul 7, 2010
    The Nikon F3AF in autofocus mode reminds me of Second City TV's "Dr. Tongue's House of 3D cats". With the host bobbing back and forth from the camera to give the 3D effect.
     
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  7. Naveed Akhtar

    Naveed Akhtar SC Regular

    186
    Dec 8, 2011
    London, UK
    Very useful post .. thanks mate!
     
  8. tattee

    tattee SC Regular

    36
    Sep 14, 2011
    Oh that's why my GXR has a hard time focusing. The shallow DOF of the GXR works against the CD-AF. Maybe adjusting the aperture to f4-f8 will improve AF performance? Or am I not making any sense? :biggrin:
     
  9. Phoenix

    Phoenix SC Top Veteran

    508
    Dec 28, 2011
    Melbourne, Australia
    Phoenix Gonzales
    I hardly use AF, but this is a very useful and informative read.

    cheers, buddy
     
  10. Luckypenguin

    Luckypenguin SC Hall of Famer

    Dec 24, 2010
    Brisbane, Australia
    Nic
    Funny thing about this article (dated 5 July 2010),
    "The major drawback to contrast assessment autofocus is that it is slow"

    Today, only 18 months later, look at Panasonic m4/3, Olympus m4/3, Nikon 1...

    It could even be argued that in mid 2010 the Panasonic G1, GH1, and GF1 (with the right lens) were no slouches for AF either.
     
    • Like Like x 1
  11. Naveed Akhtar

    Naveed Akhtar SC Regular

    186
    Dec 8, 2011
    London, UK
    Well don't wanna argue =] but is true. AF on my GF3 is noticeably faster than GH1 specially with the new lenses, but still GH1 got a speed that never actually make me feel its an issue of any kind. Its not fastest according to the current standards, but is always fast enough.

    Still a good article for getting some insight know how.