canon-nikon AF technology- the difference

Discussion in 'Nikon' started by Red_Baron, Oct 7, 2007.

  1. Red_Baron

    Red_Baron Guest

    Hello,

    I'm new to this group. And the reason I came here is because I need
    advice.
    I have to write a comparison between Canon and Nikon autofocus
    solutions (used in SLR cameras). Having in mind I'm a total newbie,
    could you advise me where (and how) to look for the information.

    Thank you for every help,

    Roko
     
    Red_Baron, Oct 7, 2007
    #1
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  2. Red_Baron

    Scubabix Guest

    Be very careful what you ask in a forum like this. Go to your local camera
    shop and handle the cameras yourself. Then buy what you feel comfortable
    with. If you ask 3 people here which is better, Canon or Nikon, you'll get
    6 different answers. The only thing I will give as advice is that there are
    a lot of professionals out there that use either, but most I have spoken to
    use Canon. Take that as you will and enjoy the firestorm you lit by asking
    here.

    Rob
     
    Scubabix, Oct 7, 2007
    #2
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  3. Red_Baron

    frederick Guest

    Canon use in-lens focus motor, micro-motor or ultrasonic
    ring motor type (USM). Canon first implemented the system
    in EF lenses many years ago (late 1980s?), Nikon not until
    the late '90s.

    Nikon use the same systems in new lenses designated "AFS".
    Most Nikon DSLR camera bodies (notably not D40/D40x models)
    also have a motor in the body to drive older AF lenses that
    do not have a focus motor, commonly referred to as "screw
    driven" due to a slotted axle in the lens, and screwdriver
    like prong that it connects to on the camera body on the
    lens mount flange.

    Generally USM / AFS ultrasonic "ring motor" AF can be
    overridden without switching AF off on the lens or body by
    turning the focus ring. Some micro-motor AFS lenses also
    have this feature.
    Generally AFS is faster focusing than screw-driven lenses,
    but that depends on gearing ratio of the screw-driven lens
    and speed/torque of the motor in the camera (pro bodies like
    the D2h / D2x drive screw driven lenses much faster than the
    motor used in the D50, D200 etc). Some screw driven lenses
    came in different versions with different gear ratios, and
    considerable difference in focus speed. Some micro-motor
    AFS lenses focus relatively slowly (and won't focus faster
    on "pro" bodies).
    AFS / USM lenses are generally much quieter in operation
    than screw-driven AF lenses.

    There's some further description and plenty of external
    links on Wikipedia, look for Ultrasonic Motor, Canon EF Lens
    Mount, Nikon F-Mount.
     
    frederick, Oct 7, 2007
    #3
  4. Unless your name would be Manfred Albrecht Freiherr von Richthofen,
    in which case you'd be a ghost, I'd advise you to put in your
    real name. That's the one on your identity papers.

    You might want to look into Canon's web museum and use google
    with the relevant search terms.

    There's no other help you can get since you don't even give a
    hint what you want to compare --- accuracy, speed, development
    over time, the first solution for telelenses > 150mm, etc. etc.

    -Wolfgang
     
    Wolfgang Weisselberg, Oct 7, 2007
    #4
  5. Red_Baron

    flambe Guest

    All autofocus SLRs are based on a contrast maximizing system to determine
    focus.
    Honeywell developed the original method in the 1970s and holds a
    stranglehold on basic patents in the U.S.
    However the various camera companies have developed systems far more
    sophisticated than what the original patents cover, to the point where only
    the concept of determining maximum contrast, among other issues, resembles
    the original patented concept.
    Minolta challenged Honeywell, on Honeywell's own state turf courts, and
    predictably lost big time although on the merits Minolta was probably
    correct. Facts are not a necessary basis for decisions in civil courts in
    the United States unless a judge chooses to impose that standard. Judges,
    all being personal injury lawyers at heart, rarely do so. Apparently
    Minolta's Japanese executives were ill served by their American lawyers for
    not making this clear to them.
     
    flambe, Oct 7, 2007
    #5
  6. Red_Baron

    frederick Guest

    To the OP:
    Despite Manfred von Richthofen's achievements, the Germans
    lost that war and the next one - so I'd suggest that
    Wolfie's demands for your real name and identity papers
    should be safely ignored.
     
    frederick, Oct 7, 2007
    #6
  7. Red_Baron

    Guest Guest

    nope, they're based on phase comparison with dedicated sensors behind
    the main mirror, on both film and digital slrs. the only exception
    (right now) is the nikon d3 and d300 with their 'tripod mode' live
    view, where they use contrast to focus via the main sensor without
    needing to drop the mirror to use the dedicated focus sensors. in all
    other modes on those two cameras, the normal phase detection sensors
    are used.
     
    Guest, Oct 7, 2007
    #7
  8. Red_Baron

    Red_Baron Guest

    Maybee I wasn't clear enough. I'm not buying anything. I have to write
    a comparison for one subject at the University. What do I want to
    compare? Have no idea, I guess everything. Actually the only thing I'm
    not interested is which af solution is better, rather the pros and
    cons of both. Thank you for the information, and especially for the
    keywords! I'll make some googling and will ask if I have any more
    questions.

    @wolfgang
    Sorry for using your famous history person's nickname for an alias.
    Hope you have no hard feelings about it.
     
    Red_Baron, Oct 8, 2007
    #8
  9. Red_Baron

    frederick Guest

    Then AFAIK, you're effectively stuffed.
    There's no difference these days. Canon's was better, but
    Nikon, some third party lens makers, and some other camera
    manufacturers now offer the same system, and some (not
    Canon) offer integration of their old AF system with new
    cameras.
     
    frederick, Oct 8, 2007
    #9
  10. Well ... Canon has the 45 point AF in their top of the line
    cameras. Nikon surely has their own small differences. Otherwise,
    you'll be comparing sliced bread to sliced bread and discussing
    which one is better sliced and why.
    I don't care how you call yourself, but it is considered good
    manners to use ones own name in the Usenet (though some groups
    are different --- but then you'd probably not want to post about
    abuse or alcoholism under your name).

    There seems to be a strong correlation of bad behavior and having
    only an obvious nickname, as well.

    -Wolfgang
     
    Wolfgang Weisselberg, Oct 8, 2007
    #10
  11. Red_Baron

    RichA Guest

    Nikon's works?
     
    RichA, Oct 9, 2007
    #11
  12. Congratulations on being as wrong as it is possible to get in one
    sentence!

    P&S cameras generally use contrast maximising AF.
    SLRs generally use Phase Correlation (sometimes called Phase detection)
    AF, although a couple with live view have recently been introduced with
    contrast AF in that mode.

    To the OP, for a good explanation of PCAF, including how it is a direct
    derivation of the split image viewfinder on SLRs see:
    http://doug.kerr.home.att.net/pumpkin/Split_Prism.pdf

    This doesn't discuss differences between the Nikon & Canon AF systems,
    but once you understand how the basic system works the differences
    between the two systems should become clearer.
     
    Kennedy McEwen, Oct 9, 2007
    #12
  13. Whilst they offer the same AF system, they are not the same performance.

    Nikon, for example, does not offer a High Precision AF sensor at all
    whilst all of Canon's cross sensors are High Precision in the vertical
    axis.
     
    Kennedy McEwen, Oct 9, 2007
    #13
  14. Red_Baron

    acl Guest

    Not true! Here's a wronger version of his sentence:
    All yellow, square freedoms are based on twenty contrast maximizing
    system to determine
    focus.

    Notice the two category errors and the singular/plural mismatch, both
    not present originally.

    I agree, however, that it's as wrong as it can be if you mean
    factually wrong and also restrict the sentence to refer to AF systems
    (although I haven't tried constructing more wrong versions with these
    constraints).
    Yes I agree, an excellent writeup.
     
    acl, Oct 9, 2007
    #14
  15. Red_Baron

    Red_Baron Guest

    Thank you for this excellent article.
     
    Red_Baron, Oct 10, 2007
    #15
  16. Red_Baron

    frederick Guest

    The D3 and D300 do have 15 cross type sensors. Even the
    D200 has one.

    AFAIK, on all Nikon dslrs, AF is not disabled with lens
    apertures smaller than f5.6.

    Who knows how well the "scene recognition" system works?

    Sure there are some differences. Most notably, Canon's
    latest system in the 1dIII doesn't work very well.
    7 pages of reading here:
    http://www.robgalbraith.com/bins/multi_page.asp?cid=7-8740-9068

    YMMV
     
    frederick, Oct 10, 2007
    #16
  17. But do they have high sensitivity sensors?

    As in, basically a second split screen (again both horizontal
    and vertical) that blanks out above f/3.0 or so intead of about
    f/8 or so because they have a longer baseline, translating into
    more sensitivity to in-focus/not in-focus?
    The Canon 20D's AF works with a f/2.8 - 2.0x - 1.4x - 20D setup,
    i.e. effectively f/8 (the camera only sees f/5.6, IIRC). Though
    I wouldn't expect any wonders out of it, as it's driven well out
    of spec ...
    Has nothing to do with AF capability, only with automatically
    choosing exposure and aperture.
    Sure.
    The AF seems to have a problem on very bright, warm days.
    It's good to hear you are living only in bright, sunny days.
    Not necessarily all of them true or correct.

    -Wolfgang
     
    Wolfgang Weisselberg, Oct 10, 2007
    #17
  18. Indeed they do, however all cross type sensor is NOT a high precision
    sensors!
    Precisely - they are standard precision AF sensors! To get high
    precision you NEED a larger baseline which, in the case of phase
    comparison AF, MEANS a smaller f/#. It is the larger baseline that
    permits you to get AF precision to within 1/3 of the DOF, as opposed to
    Nikon's standard within DOF precision which, quite frankly, any SLR
    manufacturer can achieve.

    Which Nikon cameras sport f/2.8 or lower (ie. high precision) AF
    sensors? None of their current range appear to, but perhaps they did
    something in the past.

    BTW, AF is not disabled in Canon cameras with less than f/5.6. High
    precision AF is unavailable with lenses of such apertures, but standard
    precision remains.
     
    Kennedy McEwen, Oct 10, 2007
    #18
  19. Red_Baron

    frederick Guest

    As I understand it - yes.
    The vertical sensor is optimised for wide apertures.
    No - apparently not with the Cam 3500 system in the D300 and
    D300. It's used somehow for a focus point selection and
    tracking system.
    That's true. But even that's okay as we play cricket where
    for most of the game the players are cemented in one spot
    for up to hours on end. You could make do with a 1DIII as a
    cricket cam if you switch AF off.
     
    frederick, Oct 10, 2007
    #19
  20. Red_Baron

    frederick Guest


    Since at least the D2H Cam 2000 system, Nikon calls it's
    cross sensor AF system "high precision".
    If you know that it isn't, then perhaps you can provide a
    cite for the OP to follow up on explaining exactly how both
    systems operate with pros _and_ cons of both systems (not
    marketing "white paper" BS)

    Sorry, but "AF precision to within 1/3 of the DOF"
    definitely sounds to me like something written by a
    marketing guy.
     
    frederick, Oct 10, 2007
    #20
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