Canon 30D question

Discussion in 'Digital Photography' started by Eatmorepies, May 1, 2007.

  1. Eatmorepies

    Eatmorepies Guest

    Hello

    I used my 30D with my 70-200mm f2.8L at a cycle race. The lens is usually
    pin sharp.

    My question is about servo focus.

    I photogaphed riders coming towards me on servo focus at f3.5 with the lens
    in the 140mm region. I took pictures at about 5 to 7m. The results were not
    as sharp as I expected. I was under the impression that the camera had
    predicitive autofocus and could take account of motion of the riders. If
    this is not the case then I can understand why the pictures were less than
    pin sharp, the riders could move a few centimetres in the time taken for the
    mirror to move up. I didn't have camera shake as I was on about 1/1000s and
    was leaning on a tree.

    Is the problem as simple as riders coming closer in the 130ms or so for the
    camera to respond to the shutter?

    Regards

    John
     
    Eatmorepies, May 1, 2007
    #1
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  2. Eatmorepies wrote:

    > Hello
    >
    > I used my 30D with my 70-200mm f2.8L at a cycle race. The lens is usually
    > pin sharp.
    >
    > My question is about servo focus.
    >
    > I photogaphed riders coming towards me on servo focus at f3.5 with the
    > lens in the 140mm region. I took pictures at about 5 to 7m. The results
    > were not as sharp as I expected. I was under the impression that the
    > camera had predicitive autofocus and could take account of motion of the
    > riders. If this is not the case then I can understand why the pictures
    > were less than pin sharp, the riders could move a few centimetres in the
    > time taken for the mirror to move up. I didn't have camera shake as I was
    > on about 1/1000s and was leaning on a tree.


    I do not know of any dSLR cameras that has such a predicitive autofocus
    system as you describe... (correct me if I'm wrong). but I sure would have
    liked to had one. I do a lof of this kind of shootings too:

    http://www.dahl-stamnes.net/Foto/album.php?map=Sykkel_stmbk

    --
    Jørn Dahl-Stamnes
    http://www.dahl-stamnes.net/dahls/
     
    =?ISO-8859-1?Q?J=F8rn?= Dahl-Stamnes, May 1, 2007
    #2
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  3. Eatmorepies

    Keith Baird Guest

    Jørn Dahl-Stamnes <> wrote:
    > I do not know of any dSLR cameras that has such a predicitive autofocus
    > system as you describe... (correct me if I'm wrong).


    Of Canon's current lineup, it seems only the 1D Mk.3 has predictive
    autofocus. It's not a feature I need much, but I'm surprised it hasn't
    been carried over more from Canon's film SLRs.

    --/<eith
     
    Keith Baird, May 1, 2007
    #3
  4. Eatmorepies

    jdear64 Guest

    Keith Baird wrote:
    > Jørn Dahl-Stamnes <> wrote:
    > > I do not know of any dSLR cameras that has such a predicitive autofocus
    > > system as you describe... (correct me if I'm wrong).

    >
    > Of Canon's current lineup, it seems only the 1D Mk.3 has predictive
    > autofocus. It's not a feature I need much, but I'm surprised it hasn't
    > been carried over more from Canon's film SLRs.
    >
    > --/<eith


    >From Canon's website for the 30D:

    http://www.usa.canon.com/consumer/controlleract=ModelTechSpecsAct&fcategoryid=139&modelid=12929


    Focusing Modes
    Autofocus: One-Shot AF
    Predictive AI Servo AF
    AI Focus AF (automatic switching between One-Shot/Predictive AI
    Servo AF)
    Manual Focus (MF)
     
    jdear64, May 1, 2007
    #4
  5. Eatmorepies

    Dave S Guest

    Keith Baird wrote:
    > Jørn Dahl-Stamnes <> wrote:
    >> I do not know of any dSLR cameras that has such a predicitive autofocus
    >> system as you describe... (correct me if I'm wrong).

    >
    > Of Canon's current lineup, it seems only the 1D Mk.3 has predictive
    > autofocus. It's not a feature I need much, but I'm surprised it hasn't
    > been carried over more from Canon's film SLRs.
    >
    > --/<eith


    No one likes to be told to RTFM, but page 76 of the EOS30D Instruction
    Manual says:

    If the subject approaches or retreats from the camera at a constant
    rate, the camera tracks the subject and predicts the focusing
    distance immediately before the picture is taken. This is for
    obtaining correct focus at the moment of exposure.

    Dave S.
     
    Dave S, May 2, 2007
    #5
  6. "Eatmorepies" <> wrote in message
    news:...
    > Hello
    >
    > I used my 30D with my 70-200mm f2.8L at a cycle race. The lens is usually
    > pin sharp.
    >
    > My question is about servo focus.
    >
    > I photogaphed riders coming towards me on servo focus at f3.5 with the
    > lens in the 140mm region. I took pictures at about 5 to 7m. The results
    > were not as sharp as I expected. I was under the impression that the
    > camera had predicitive autofocus and could take account of motion of the
    > riders.


    > Regards
    > John


    I've done numerous checks on this using an EOS 10D, and lately using a 5D.
    My subjects have been motorway traffic approaching me at around 55-60mph. I
    used EF135 f2, 200 f2.8 and 300 f2.8 USM lenses, and was by an overbridge.
    Tracking using AIServo and the central focus point was in general,
    excellent, unless the subject was a bland fronted coach with little detail
    for the AF to latch on to. I also noted that the 1st. shot of a series was
    quite often less sharp than later shots. Probably because I didn't give the
    camera enough time to measure the speed of the vehicle, with the shutter
    release half-pressed.
    I also use a 30D for bird photography, and have great difficulty keeping the
    central spot on any rapidly moving bird, so occasionally I get a really
    sharp shot, but not that often! (I think my EOS3 is better with its top of
    the range AF... but then I can't afford a 1 D series yet.)
    (You might do better raising the ISO and using f5.6 to f8.)

    --
    M Stewart
    Milton Keynes, UK



    --
    Posted via a free Usenet account from http://www.teranews.com
     
    Malcolm Stewart, May 2, 2007
    #6
  7. Keith Baird wrote:

    > Jørn Dahl-Stamnes <> wrote:
    >> I do not know of any dSLR cameras that has such a predicitive autofocus
    >> system as you describe... (correct me if I'm wrong).

    >
    > Of Canon's current lineup, it seems only the 1D Mk.3 has predictive
    > autofocus. It's not a feature I need much, but I'm surprised it hasn't
    > been carried over more from Canon's film SLRs.


    I shall check that... WHEN my KmII arrive... :)
    --
    Jørn Dahl-Stamnes
    http://www.dahl-stamnes.net/dahls/
     
    =?ISO-8859-1?Q?J=F8rn?= Dahl-Stamnes, May 2, 2007
    #7
  8. Dave S wrote:

    > Keith Baird wrote:
    >> Jørn Dahl-Stamnes <> wrote:
    >>> I do not know of any dSLR cameras that has such a predicitive autofocus
    >>> system as you describe... (correct me if I'm wrong).

    >>
    >> Of Canon's current lineup, it seems only the 1D Mk.3 has predictive
    >> autofocus. It's not a feature I need much, but I'm surprised it hasn't
    >> been carried over more from Canon's film SLRs.
    >>
    >> --/<eith

    >
    > No one likes to be told to RTFM, but page 76 of the EOS30D Instruction
    > Manual says:
    >
    > If the subject approaches or retreats from the camera at a constant
    > rate, the camera tracks the subject and predicts the focusing
    > distance immediately before the picture is taken. This is for
    > obtaining correct focus at the moment of exposure.


    You're right. That was a part of the, so called, instruction manual that I
    have missed.
    --
    Jørn Dahl-Stamnes
    http://www.dahl-stamnes.net/dahls/
     
    =?ISO-8859-1?Q?J=F8rn?= Dahl-Stamnes, May 2, 2007
    #8
  9. Keith Baird wrote:
    > Jørn Dahl-Stamnes <> wrote:
    >> I do not know of any dSLR cameras that has such a predicitive autofocus
    >> system as you describe... (correct me if I'm wrong).

    >
    > Of Canon's current lineup, it seems only the 1D Mk.3 has predictive
    > autofocus. It's not a feature I need much, but I'm surprised it hasn't
    > been carried over more from Canon's film SLRs.


    All modern SLR cameras that I am aware of have predictive
    autofocus. It was introduced in film cameras in the
    late 1980s/early 1990s. All canon's DSLR I believe have
    it (I've used it on D60, 10D, 20D, 30D, 1D Mark II).

    Roger
     
    Roger N. Clark (change username to rnclark), May 3, 2007
    #9
  10. Eatmorepies wrote:
    > Hello
    >
    > I used my 30D with my 70-200mm f2.8L at a cycle race. The lens is usually
    > pin sharp.
    >
    > My question is about servo focus.
    >
    > I photogaphed riders coming towards me on servo focus at f3.5 with the lens
    > in the 140mm region. I took pictures at about 5 to 7m. The results were not
    > as sharp as I expected. I was under the impression that the camera had
    > predicitive autofocus and could take account of motion of the riders. If
    > this is not the case then I can understand why the pictures were less than
    > pin sharp, the riders could move a few centimetres in the time taken for the
    > mirror to move up. I didn't have camera shake as I was on about 1/1000s and
    > was leaning on a tree.
    >
    > Is the problem as simple as riders coming closer in the 130ms or so for the
    > camera to respond to the shutter?


    John,

    Are you using a single autofocus sensor, or all AF points at once?
    I think multiple sensors can get confused by static background
    spots versus moving spots. I have found I get better
    tracking when I use 1 AF point. I have used a D60,
    10D, and 1D Mark II for wildlife action photography.
    I have found the 1DII is much much better at predictive
    autofocus than the 10D or D60. I now also have a 30D but I
    have not had a chance to use it yet for moving subjects
    (maybe this weekend).

    Roger
    http://www.clarkvision.com
     
    Roger N. Clark (change username to rnclark), May 3, 2007
    #10
  11. In article <> "Roger N. Clark (change username to rnclark)" <> writes:
    $Are you using a single autofocus sensor, or all AF points at once?
    $I think multiple sensors can get confused by static background
    $spots versus moving spots.

    The camera will typically pick the closest potential subject, so
    this shouldn't be an issue if the cyclist on whom you're trying to
    focus is the closest thing that's under any AF point, although if
    you have an AF point on (for example) a painted line on the pavement
    in front of the cyclist, it's possible that the camera might lock
    onto that.

    AF is faster on most if not all EOS bodies if you manually select
    one AF point. If you leave all AF points enabled, the camera's AF
    system has to evaluate each one, and it only has so much CPU power
    to do this. If you pick one manually, the camera ignores all the
    others and AF becomes quicker.

    I'm not sure if any of the AF points in the 30D are quicker
    than the others when manually selected; this is the case in some
    bodies but not necessarily all, and if one is quicker than the others,
    it's central one. The central point has the advantage of being a
    cross-type sensor, so it can lock onto just about any edge, whether
    horizontal, vertical, or diagonal. With the original poster's 70-200/2.8,
    the central sensor has another advantage: it will operate in
    high-precision mode.

    Another guess about a potential reason for the OP's problem:
    perhaps the shutter speed wasn't high enough to freeze the cyclist's
    motion.

    Some lenses' AF hardware (motors, gear trains, etc.) would not
    be fast enough for sports shooting, but unless there's something
    wrong with the OP's lens, that won't be an issue here; the 70-200's
    AF hardware is quick and well suited for sports shooting.
    --
    Stephen M. Dunn <>
    >>>----------------> http://www.stevedunn.ca/ <----------------<<<

    ------------------------------------------------------------------
    Say hi to my cat -- http://www.stevedunn.ca/photos/toby/
     
    Stephen M. Dunn, May 4, 2007
    #11
  12. Stephen M. Dunn wrote:
    > In article <> "Roger N. Clark (change username to rnclark)" <> writes:
    > $Are you using a single autofocus sensor, or all AF points at once?
    > $I think multiple sensors can get confused by static background
    > $spots versus moving spots.
    >
    > The camera will typically pick the closest potential subject, so
    > this shouldn't be an issue if the cyclist on whom you're trying to
    > focus is the closest thing that's under any AF point, although if
    > you have an AF point on (for example) a painted line on the pavement
    > in front of the cyclist, it's possible that the camera might lock
    > onto that.


    This is not the case in my experience. All the cameras I have used,
    Canon D60, 20D, 30D, 1D Mark II, plus a variety of point and shoots
    all are biased to the highest contrast thing on an AF sensor.
    For example, follow a bird in for a landing, with blue sky for the
    background with all AF points on. As the bird drops, and other
    backgrounds come into view, like trees or mountains, the camera
    usually switches focus to the background, and in a line of
    photographers tracking the bird, you'll hear a number of them
    starting to curse--they have all focus point on. Those
    who have one AF on, and are able to keep the AF point on the bird
    have no problem.

    Yesterday I photographed my son's graduation from college.
    I tested focus of people walking across the stage. With all focus
    points on, things on the stage grabbed focus, both in front
    or behind the subject depending on contrasts. I used 1 AF point
    and tracked people walking with no problem.

    Some action examples using one AF point, predictive (AI) mode:

    http://www.clarkvision.com/galleries/gallery.africa/web/cheetah.c01.26.2007.JZ3F2435c-700.html

    http://www.clarkvision.com/galleries/gallery.africa/web/eagle.c01.18.2007.JZ3F7355b-700.html

    http://www.clarkvision.com/galleries/gallery.africa/web/lion.cubs.c01.21.2007.JZ3F8911.b-700.html

    http://www.clarkvision.com/galleries/gallery.bear/web/brown_bear.c09.07.2004.JZ3F0862.b-700.html

    http://www.clarkvision.com/galleries/gallery.bear/web/brown_bear.c09.09.2004.JZ3F4246.b-700.html

    http://www.clarkvision.com/galleries/gallery.bird/web/eagle.c09.11.2004.JZ3F4717.b-700.html

    Roger
     
    Roger N. Clark (change username to rnclark), May 6, 2007
    #12
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