AF points

Discussion in 'Digital Photography' started by Mike, Dec 1, 2003.

  1. Mike

    Mike Guest

    Excuse the basic question, but on the Canon 10D I am having difficulty
    understanding the advantage of having 7 AF points. I usually shoot in manual
    mode and I am very happy with the results from this camera. But I would like
    to understand more about the benefits of having so many AF points. Why not
    just select the centre one, lock focus on subject, recompose and then shoot?
    Why bother selecting the AF point that best suits the composition? I know
    there must be a very important reason and I am missing something very
    obvious. Any help appreciated.
     
    Mike, Dec 1, 2003
    #1
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  2. Mike

    zbzbzb Guest

    >
    >Excuse the basic question, but on the Canon 10D I am having difficulty
    >understanding the advantage of having 7 AF points. I usually shoot in manual
    >mode and I am very happy with the results from this camera. But I would like
    >to understand more about the benefits of having so many AF points. Why not
    >just select the centre one, lock focus on subject, recompose and then shoot?
    >Why bother selecting the AF point that best suits the composition? I know
    >there must be a very important reason and I am missing something very
    >obvious. Any help appreciated.


    About the only reason I could see is for following a moving subject while
    manitaining focus. Other than that the camera is merely guessing at what it is
    you want it to focus on. On my Canon Elan IIe I only used the center focusing
    point and I would simply lock the focus with the rear AE lock button customized
    to activate AF. I found it silly to have 5 focus points
     
    zbzbzb, Dec 1, 2003
    #2
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  3. bzbzb (zbzbzb) writes:

    > About the only reason I could see is for following a moving subject while
    > manitaining focus. Other than that the camera is merely guessing at what it is
    > you want it to focus on. On my Canon Elan IIe I only used the center focusing
    > point and I would simply lock the focus with the rear AE lock button customized
    > to activate AF. I found it silly to have 5 focus points
    >


    Canon Elan IIe has only 3 AF points (check e.g.
    http://www.canon.com/camera-museum/camera/1992-1996/data/1995_eos55_s.html)
    so the amount of silliness is not too bad (only 2 AF points over those
    actually needed).

    Bye, Dragan

    --
    Dragan Cvetkovic,

    To be or not to be is true. G. Boole No it isn't. L. E. J. Brouwer

    !!! Sender/From address is bogus. Use reply-to one !!!
     
    Dragan Cvetkovic, Dec 1, 2003
    #3
  4. Mike

    Todd Walker Guest

    In article <bqfovh$j8n$>,
    says...
    > Excuse the basic question, but on the Canon 10D I am having difficulty
    > understanding the advantage of having 7 AF points. I usually shoot in manual
    > mode and I am very happy with the results from this camera. But I would like
    > to understand more about the benefits of having so many AF points. Why not
    > just select the centre one, lock focus on subject, recompose and then shoot?
    > Why bother selecting the AF point that best suits the composition? I know
    > there must be a very important reason and I am missing something very
    > obvious. Any help appreciated.


    I keep mine set on the center focus point most of the time but just this
    past weekend I had a situation where the multiple points came in handy.
    I was taking Santa pictures at a local children's store and I had my
    camera mounted in portrait orientation on a tripod. I always focus on
    the eyes and in this situation, the eyes weren't in line with the center
    focus point, so I selected the point that did fall on the eyes and it
    worked like a charm. With the camera on a tripod in basically a fixed
    position, it would have been very hard to lock focus and recompose,
    especially shooting pics of kids where timing is of the essence :)

    --
    __________________________________
    Todd Walker
    http://www.toddwalker.net
    Canon 10D page:
    http://www.toddwalker.net/canon10d
    __________________________________
     
    Todd Walker, Dec 1, 2003
    #4
  5. Mike

    zbzbzb Guest

    zbzbzb, Dec 1, 2003
    #5
  6. Mike wrote:

    > Excuse the basic question, but on the Canon 10D I am having difficulty
    > understanding the advantage of having 7 AF points. I usually shoot in manual
    > mode and I am very happy with the results from this camera. But I would like
    > to understand more about the benefits of having so many AF points. Why not
    > just select the centre one, lock focus on subject, recompose and then shoot?
    > Why bother selecting the AF point that best suits the composition? I know
    > there must be a very important reason and I am missing something very
    > obvious. Any help appreciated.


    The D100 has 5 points. I use the upper one for shooting people so there
    face is not in the center of the shot. I use the two side ones for
    situation involving two people side by side. The right one is handy
    when shooting people in verticals. I haven't really found a use for the
    bottom one.

    I leave it on center most of the time but since it's really easy to
    change from the back of the camera I do use the other points as the
    situation requires. If I am going to be shooting a lot of pictures
    where an alternate focus point will save time, I change it.
     
    Andrew McDonald, Dec 1, 2003
    #6
  7. Mike

    Azzz1588 Guest

    In article <>,
    bzbzb (zbzbzb) writes:

    >You are right. I also had an A2 which is the one that had the 5 points.
    >Either
    >way it was silly for typical use.




    First thing I turned off with my C 4040Z (iESP)
    Silly isnt the word for it.............
























    "Only a Gentleman can insult me, and a true Gentleman never will..."
     
    Azzz1588, Dec 1, 2003
    #7
  8. Mike

    zbzbzb Guest

    >>You are right. I also had an A2 which is the one that had the 5 points.
    >>Either
    >>way it was silly for typical use.

    >
    >
    >
    >First thing I turned off with my C 4040Z (iESP)
    >Silly isnt the word for it.............


    I also killed the 9 point AF in the A80 in the first few pics.
     
    zbzbzb, Dec 1, 2003
    #8
  9. Mike

    Christian Guest

    Mike wrote:

    > Excuse the basic question, but on the Canon 10D I am having difficulty
    > understanding the advantage of having 7 AF points. I usually shoot in
    > manual mode and I am very happy with the results from this camera. But I
    > would like to understand more about the benefits of having so many AF
    > points. Why not just select the centre one, lock focus on subject,
    > recompose and then shoot? Why bother selecting the AF point that best
    > suits the composition? I know there must be a very important reason and I
    > am missing something very obvious. Any help appreciated.


    The advantage is that you don't need to worry about exposures because both
    ambient and flash exposures are linked to the selected AF point. So, for
    example, if you lock the focus and then recompose without using AEL/FEL
    then in many circumstances you will get a poor exposure. If you let the
    camera select the AF point then you should get better exposures.

    This disadvantage of letting the camera select the AF point is that it is
    slower and sometimes the camera will get it wrong. There is also a lack of
    control (for example, if you are using a shallow DOF and want to focus on
    the subject's eyes).
     
    Christian, Dec 2, 2003
    #9
  10. Mike

    Chris Brown Guest

    In article <bqgskq$7f8$>,
    Christian <> wrote:

    >The advantage is that you don't need to worry about exposures because both
    >ambient and flash exposures are linked to the selected AF point.


    You sure about the ambient thing? I'm pretty certain that partial metering
    always uses the centre circle regardless. I don't know about Evaluative and
    Centre Weighted, I never use them.

    Actually, after the novelty of having 7 AF points wore off, I just disabled
    the other 6. They just seemed to get in the way. Having dedicated buttons
    for autofocus and FEL helps enormously.
     
    Chris Brown, Dec 2, 2003
    #10
  11. Mike

    zbzbzb Guest

    >>The advantage is that you don't need to worry about exposures because both
    >>ambient and flash exposures are linked to the selected AF point.

    >
    >You sure about the ambient thing? I'm pretty certain that partial metering
    >always uses the centre circle regardless. I don't know about Evaluative and
    >Centre Weighted, I never use them.



    If things haven't changed then only Canon's evaluative metering mode is linked
    and weighted towards the focusing point in use. My Elan IIe was like that so I
    only used the partial mode most times like you do.
     
    zbzbzb, Dec 2, 2003
    #11
  12. >>First thing I turned off with my C 4040Z (iESP)
    >
    >I also killed the 9 point AF in the A80 in the first few pics.



    Same here. The AF always focused on objects behind the subject of my shots,
    which were generally in the center. That, however, could have been because the
    subject was a 5 year old. :)
     
    Kerry Sanders, Dec 6, 2003
    #12
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