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Thread: 7 compared to 9 focus point

  1. #1

    Default 7 compared to 9 focus point

    Are there any significant differences between a system with 7 point focus compared to 9?

    thanks.

  2. #2
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    Default Re: 7 compared to 9 focus point

    Pardon the obvious answer, but 2 focusing points?

    Where those two points are will impact how often you might wish to use them (and therefore how much you might miss them not being there).

    But far more important in the choice of an AF system is general performance. For most purposes I would take a desperately fast and accurate single point system over an average 7 or 9 point system where all of the satellite points are line rather than cross sensors, and prone to hunting frequently.

    If both systems are similar, then really the answer is... 2 focusing points.

  3. #3

    Default Re: 7 compared to 9 focus point

    hi Jed,

    are you saying that a single point system is faster in focusing than 7,9 or more focus point systems? (e.g. nikons 51point)

    then what's the purpose of so many focus point.. (to get sharper pic)?

    i'm not sure... just asking.

  4. #4

    Default Re: 7 compared to 9 focus point

    Quote Originally Posted by Bryaan View Post
    hi Jed,

    are you saying that a single point system is faster in focusing than 7,9 or more focus point systems? (e.g. nikons 51point)

    then what's the purpose of so many focus point.. (to get sharper pic)?

    i'm not sure... just asking.
    Tracking the subject as well as telling which part of the picture should be most focused.
    You wont see me much less remember me but i am the guy who makes you look good.

  5. #5

    Default Re: 7 compared to 9 focus point

    are you saying that a single point system is faster in focusing than 7,9 or more focus point systems? (e.g. nikons 51point)

    then what's the purpose of so many focus point.. (to get sharper pic)?
    Actually, not all the 51 AF points are selectable. Like Canon's EOS-1 DSLRs, they all have 45 AF Points but only 19 are selectable and the other 26 are 'assist' points which are adjacent to the 19 selectable, purely to assist focusing when doing things like tracking a moving subject. It's like having more eyes tracking on a subject. You won't get a sharper picture but some photographers, especially when they use wide aperture settings where the Depth of Field is shallow, they'd rather use the focusing point nearest to the subject they wanna focus on as opposed to using the centre point and recomposing the frame which may cause shifting of the focal plane which may result in an OOF image of the subject, if not, not as sharp.

    That said, majority of the latest consumer DSLR models, 450D, 500D, have the centre point as the most accurate AF point, they call these sensitive and accurate points as 'Cross type'. The EOS-1, 7D, xxD have cross type for all AF points while the 5D, and latest xxxD have centre as the cross type. Accuracy and speed of AF is also dependent on the lens used.
    Last edited by rendition; 9th October 2009 at 11:53 AM.

  6. #6
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    Default Re: 7 compared to 9 focus point

    Quote Originally Posted by Bryaan View Post
    are you saying that a single point system is faster in focusing than 7,9 or more focus point systems? (e.g. nikons 51point)

    then what's the purpose of so many focus point.. (to get sharper pic)?
    Hi Bryaan,

    No, I'm saying a single point system *can* be better. But it is not in any way guaranteed or even likely to be better.

    Although all things being equal a camera focusing all it's processing power on one point means that it probably will be (slightly) better, as it doesn't have to worry about what the other focusing points are or should or could be doing. (Refer to gymnastics example below)

    I'm struggling to think of the last camera that only had one focusing point, but as an example I would take say a Nikon F90x (one point) over a Canon EOS 500 (three points).

    Some of the early multipoint cameras like the Nikon F5 had very dubious multipoint systems. For example the top and bottom of its five points were line sensors and only capable of distinguishing contrast in one plane, which made them largely unuseable. The focusing points were fairly wide apart and therefore the whole concept of 3D tracking (or whatever it was called) tended to be more miss than hit. And quite simply, the technology of the day and the computing power simply wasn't there for the system to work in anything other than tracking a subject against a clean background. Any hint of detail in the background and the system would happily jump to that instead.

    These days more focusing points also tends to imply better sensors, better processing capability, and better flexibility with using them. And usually they can keep up with the majority of situations although I wouldn't use 51 points in my cameras except in the no-contrast situation described above.

    But even today, a 51 (or however many) point system can be improved by switching all but one off, should you need the accuracy and raw processing power. For example if I am shooting something fast moving (gymnastics, greyhound racing, etc) then I will generally switch to a single AF point. This is particularly true if the situation is complicated by other factors that stress AF - contrasty background, low light levels (gymnastics meets this scenario very well).

    In this situation the camera is handicapped by constantly looking at it's "other" focusing points, processing the data from them, possibly getting confused by them.

    More focusing points... give you the freedom to select a single AF point at different parts of the frame to aid composition. They can also help you track erratically moving subjects that you cannot keep on a given AF point, given the right conditions. Even in this case more is not merrier - my cameras are always run on 1, 9 or 21 points as a Nikon user that has 51 available.

  7. #7

    Default Re: 7 compared to 9 focus point

    ok! thanks all for the information!

    has been helpful much

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    Default Re: 7 compared to 9 focus point

    Quote Originally Posted by rendition View Post
    Actually, not all the 51 AF points are selectable. Like Canon's EOS-1 DSLRs, they all have 45 AF Points but only 19 are selectable and the other 26 are 'assist' points which are adjacent to the 19 selectable, purely to assist focusing when doing things like tracking a moving subject.
    Actually, you'll find that they are.

  9. #9

    Default Re: 7 compared to 9 focus point

    Quote Originally Posted by rendition
    Actually, not all the 51 AF points are selectable. Like Canon's EOS-1 DSLRs, they all have 45 AF Points but only 19 are selectable and the other 26 are 'assist' points which are adjacent to the 19 selectable, purely to assist focusing when doing things like tracking a moving subject.
    the 51 pts on the new nikon pro cameras are all selectable.

  10. #10

    Default Re: 7 compared to 9 focus point

    Oh really? Oopsy... then whoa, TS... get it. Haha.

    Presently on the 1DIII, I have the 'inner points' set and already find it more than enough.

  11. #11

    Default Re: 7 compared to 9 focus point

    Well, it also depend on what the shooter want.
    eg. Requirement for landscape and portrait will be different.

    Personally, i dont have problem with 're-compose' for landscape,
    but 're-compose' is no-no if i shoot portrait with fast lens, at least for my taste.

    Btw the number of AF point, its also good to know how far they are apart.
    most AF point crowd around the center portion of the frame,
    (anyone know why ?)
    I would prefer to have a 11 AF Pt equally spread out than 52-pt crowd near the center.

  12. #12

    Default Re: 7 compared to 9 focus point

    Quote Originally Posted by rendition View Post
    Actually, not all the 51 AF points are selectable. Like Canon's EOS-1 DSLRs, they all have 45 AF Points but only 19 are selectable and the other 26 are 'assist' points which are adjacent to the 19 selectable, purely to assist focusing when doing things like tracking a moving subject.
    On a 1D MkII, all 45 points are selectable. Additionally, double points can also be selected.

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    Default Re: 7 compared to 9 focus point

    Quote Originally Posted by Dream Merchant View Post
    On a 1D MkII, all 45 points are selectable. Additionally, double points can also be selected.
    Lol

    Actually, regarding 11 spread points v 51 bunched points, assuming you consider a situation similar to the D2 series and the D300/D700/D3 cameras, then personally, no I would take the 51.

    Firstly the 51 points can be reduced to 11 as an option, so there is always that option to do that. But 11 points I found was frequently just not quite right when trying to nail specific focus on an eye for example. And also when tracking, the distance between points again led to problems with "passing" the subject from one point to another.

    While I am sure the better processing power these days helps a lot, I suspect the closeness of the points contributes significantly to the new system's ability to tag a subject and stay on it without jumping to the background.

    The F5 did the background jump (horribly), the D1s did the background jump, the D2s did relatively common background jumps, and the D300/D700/D3s... well they simply don't.

  14. #14

    Default Re: 7 compared to 9 focus point

    Quote Originally Posted by Dream Merchant
    On a 1D MkII, all 45 points are selectable. Additionally, double points can also be selected.
    In manual AF selection mode? Unless I've missed a section in the manual guide, please share with me how this is possible.
    Last edited by rendition; 10th October 2009 at 01:11 PM.

  15. #15

    Default Re: 7 compared to 9 focus point

    Quote Originally Posted by rendition View Post
    In manual AF selection mode? Unless I've missed a section in the manual guide, please share with me how this is possible.
    he referring to the mark 2. mark 3 only has 19 selectable points.

  16. #16

    Default Re: 7 compared to 9 focus point

    LOL! Sorry for the confusion Rendition, but you did say "Like Canon's EOS-1 DSLRs" referring to ALL 1 series cameras.

    Jed, again, I'm speaking about the 1DMkII - jumping to the BG. The speed or sensitivity of which can be set via custom functions meaning that in use, if I set the speed of the 'jump' appropriately, I won't have the AF jumping to the BG (or foreground or interrupting subjects/objects) or I may choose to have it jump back and forth very very quickly.

    Again, there are other parameters of AF point/AF customizability that determines how the 1DMkII's AF system behaves, what it picks up and how it picks it up.

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    Default Re: 7 compared to 9 focus point

    Quote Originally Posted by Dream Merchant View Post
    Jed, again, I'm speaking about the 1DMkII - jumping to the BG. The speed or sensitivity of which can be set via custom functions meaning that in use, if I set the speed of the 'jump' appropriately, I won't have the AF jumping to the BG (or foreground or interrupting subjects/objects) or I may choose to have it jump back and forth very very quickly.

    Again, there are other parameters of AF point/AF customizability that determines how the 1DMkII's AF system behaves, what it picks up and how it picks it up.
    My LOL was directed at rendition's comment about 1 series cameras after what you said

    Not commenting about Canons as I don't have enough experience about whether or not their multiple point system is good enough or when it made that transition if it did!

  18. #18

    Default Re: 7 compared to 9 focus point

    focus points are useless. all i need is one, the center one.

  19. #19

    Default Re: 7 compared to 9 focus point

    more focus point are usefull when u are doing bokeh shot.
    it easy that way once u had frame u object
    frame ---> focus ----> shot

    ps: v usefull for Portraits
    Last edited by Ryusei; 10th October 2009 at 09:02 PM.
    Thank & Best Reg
    Ryusei kit lens & 1.8/50mm lens

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    Default Re: 7 compared to 9 focus point

    Quote Originally Posted by rendition View Post
    Oh really? Oopsy... then whoa, TS... get it. Haha.

    Presently on the 1DIII, I have the 'inner points' set and already find it more than enough.
    isn't there a custom function on the 1d that lets you choose how many you can select... i have all 45 selectable on my 1dII...

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