Results 1 to 18 of 18

Thread: please explain 11 point focus' proper use?

  1. #1

    Default please explain 11 point focus' proper use?

    Hi seniors:

    would basic questions be too "duhhh" here? I am a newbie transiting to DSLR, so really want to know some of the cool features that pros use.. thus need to ask, so i can learn =)

    first up.. 11 point focus. this is a feature i dun see in P&S. Can someone explain to me how pros find this useful, compared to the normal way of pointing at object, focus, den shift the camera to recompose the shot?

    =)

  2. #2
    Senior Member darrrrrrrrrr's Avatar
    Join Date
    Sep 2006
    Location
    Singapore
    Posts
    3,208

    Default Re: please explain 11 point focus' proper use?

    Quote Originally Posted by silverspear View Post
    Hi seniors:

    would basic questions be too "duhhh" here? I am a newbie transiting to DSLR, so really want to know some of the cool features that pros use.. thus need to ask, so i can learn =)

    first up.. 11 point focus. this is a feature i dun see in P&S. Can someone explain to me how pros find this useful, compared to the normal way of pointing at object, focus, den shift the camera to recompose the shot?

    =)
    at least you know how to focus then recompose

    with shallow DOF on a FA50 lens, for example, you will have so shallow DOF that the movement of recomposing might cause the subject to shift off the focus plane, so you pick the closest AF point to minimise that movement. also it prevents you from looking like a twitching monkey with all that pointing here and there.

    if you are shooting sports on AF-C and you have a pre-visualised composition, you might want to pick an off-centre AF point and use that to track the subject rather than fiddling with configuring the AF/OK button to enable/disable AF so you can recompose.

    if you are shooting landscapes on a tripod you could select a AF point to AF with rather than fiddling with the ballhead just to focus and then recompose the shot.

  3. #3
    Senior Member
    Join Date
    Mar 2007
    Location
    Still wondering where I belong
    Posts
    3,434

    Default Re: please explain 11 point focus' proper use?

    when u recompose, u hand will shift slightly, unless u can move like robot in parallel on the focus plane to the subject...

    11 point is there to help u focus when ur subject is off center, also using dslr, chances u might be using a fast lens which DOF can be thin and focus needs to be more spot on, recompose might missed...

    pns usually dof not so critical as compare to dslr...

    this is only true for dslr, but for film can some what tolerate the recompose method to a certain extent...
    Gallery|Baby gallery
    I have become an expert in cleaning poo

  4. #4

    Default Re: please explain 11 point focus' proper use?

    PnS don't have this feature, because with contrast detection you practically have infinite AF points (exaggeration.. you're limited by the megapixels and the number of pixels required to test for contrast).

    I'm not sure how a pro will find all the AF points useful also, since I think most pros will just be using center point AF. The multiple AF points I thought help newbies that don't know how to point at object, focus, shift... when you set to auto AF point select. Sometimes I do select specific AF points when I use with tripod and remote control and want to stand somewhere other than the middle of the frame.

  5. #5
    Senior Member darrrrrrrrrr's Avatar
    Join Date
    Sep 2006
    Location
    Singapore
    Posts
    3,208

    Default Re: please explain 11 point focus' proper use?

    Quote Originally Posted by woefulwabbit View Post
    PnS don't have this feature, because with contrast detection you practically have infinite AF points (exaggeration.. you're limited by the megapixels and the number of pixels required to test for contrast).

    I'm not sure how a pro will find all the AF points useful also, since I think most pros will just be using center point AF. The multiple AF points I thought help newbies that don't know how to point at object, focus, shift... when you set to auto AF point select. Sometimes I do select specific AF points when I use with tripod and remote control and want to stand somewhere other than the middle of the frame.
    no because P&S have face detection so the camera can choose the face, don't even need the operator to decide anything.

  6. #6

    Default Re: please explain 11 point focus' proper use?

    wow! darrrr, best explanaation! now i know how and when to use it =) i was like wondering the whole week why would anyone need 11 points of focus.. so troublesome now i'm wiser just abit =)

  7. #7
    Senior Member darrrrrrrrrr's Avatar
    Join Date
    Sep 2006
    Location
    Singapore
    Posts
    3,208

    Default Re: please explain 11 point focus' proper use?

    Quote Originally Posted by silverspear View Post
    wow! darrrr, best explanaation! now i know how and when to use it =) i was like wondering the whole week why would anyone need 11 points of focus.. so troublesome now i'm wiser just abit =)
    some of the nikons have 51 points for continuous, predictive AF tracking across the frame, but i don't think most users need so many, but it's good to have if you ever need to shoot BIF i guess

    anyway if my memory serves me right, the 3x3 grid are cross-type sensors so they can detect horizontal and vertical contrast, while the extreme left and right sensors are vertical line sensors (only can detect horizontal contrast). also, the AF sensor is apparently much bigger than the red-light indicator (which the k-x lacks anyway) so AF may not be so accurate and the camera could lock on something other than what you are aiming at, depending on which is more contrasty.

  8. #8
    Member banana0ne's Avatar
    Join Date
    Oct 2008
    Location
    jurong west
    Posts
    1,488

    Default Re: please explain 11 point focus' proper use?

    Panasonic Lumix PNS's have 9 point cross grid focusing but it only detects the nearest point to lock on but you don't have any option to shift the focus point manually.
    I dunno!!!
    It's banana-zero-neh. :)

  9. #9
    Senior Member darrrrrrrrrr's Avatar
    Join Date
    Sep 2006
    Location
    Singapore
    Posts
    3,208

    Default Re: please explain 11 point focus' proper use?

    why you should set your AF point selection mode to AUTO before handing your cam off to someone else:



    with them, the centre AF point is never used at all

    btw, IT IS SNOWING!

  10. #10
    Member
    Join Date
    May 2007
    Location
    Florida
    Posts
    1,984

    Default Re: please explain 11 point focus' proper use?

    Quote Originally Posted by darrrrrrrrrr View Post
    why you should set your AF point selection mode to AUTO before handing your cam off to someone else:



    with them, the centre AF point is never used at all

    btw, IT IS SNOWING!
    I feel your pain.... but hey, Woohoo! Winter wonderland! I'm jealous....

  11. #11

    Default Re: please explain 11 point focus' proper use?

    Nice and sharp trees

  12. #12

    Default Re: please explain 11 point focus' proper use?

    Quote Originally Posted by darrrrrrrrrr View Post
    why you should set your AF point selection mode to AUTO before handing your cam off to someone else:



    with them, the centre AF point is never used at all

    btw, IT IS SNOWING!
    i think the photographer is too busy appreciating the scene behind

    anyways, regarding threadstarter's question..

    also, not every scene allows you to recompose, sometimes you want a shot that you have previsualised, and you wait for the right moment.. and don't have the leisure of happily center focus + recompose.

    other than that, what darren has mentioned is very true, especially for the landscape case.

  13. #13
    Member deathstar's Avatar
    Join Date
    Jun 2008
    Location
    West End Boy
    Posts
    93

    Default Re: please explain 11 point focus' proper use?

    Where should I focus to keep both subjects in focus?

    Quote Originally Posted by darrrrrrrrrr View Post
    why you should set your AF point selection mode to AUTO before handing your cam off to someone else:



    with them, the centre AF point is never used at all

    btw, IT IS SNOWING!

  14. #14

    Default Re: please explain 11 point focus' proper use?

    Depends on your AF setting. If it is set to auto, then it should automatically pick out the two guys to focus on.
    If set to center spot... then you have to aim the center point at one of the two guys, half press shutter to allow the focus to lock on the guy, then reframe the two guys as in the image and full press the shutter release.
    If set to spot select.. then you probably don't know what you are doing

    What happened in the picture is that the person behind the camera is using center spot (or spot select center) and just frame the shot as above and fully press the shutter release.. the camera then focus on the center spot which is the background behind and then fires away.
    I don't subsidize marketing campaigns.

  15. #15

    Default Re: please explain 11 point focus' proper use?

    Well since you are asking in the Pentax forum, this bit is relevant.

    Note that the Pentax K-x does not show which point it is focusing on within the viewfinder, so even though it has an 11 point AF its somewhat useless since you cannot be sure what it is focusing on. You either have to use live view or use center point and recompose.

    Something to note if you are considering the K-x!

    (I still love it anyway!)

  16. #16

    Default Re: please explain 11 point focus' proper use?

    Yes as I've mentioned there are 3 modes:
    Spot Center - Always use the center point
    Spot Select - You can choose which of the 11 spots to use
    Auto AF (5, 9 or 11) - Camera measures distance to all 11 (or 5 or 9) AF spots and decides which one to use through some algorithm.. from my tests it looks like it will ignore the points that are far away, and tries to find a point or combination of points that covers as many nearby points as possible.
    I don't subsidize marketing campaigns.

  17. #17

    Default Re: please explain 11 point focus' proper use?

    question regarding focussing: what if taking a group of people, set to auto 11pt as well?
    how about if they are seated at a large round table such that each person is at a different distance to the camera?

  18. #18

    Default Re: please explain 11 point focus' proper use?

    Quote Originally Posted by sid8888 View Post
    question regarding focussing: what if taking a group of people, set to auto 11pt as well?
    how about if they are seated at a large round table such that each person is at a different distance to the camera?
    The nice thing about a round table (e.g. in weddings) is that everyone standing/sitting at one side to face the camera will naturally curve and remain somewhat equi-distance to the camera. It's not perfect, of course... and anyway you always want to focus on the couple

    If it's just a general table shot and not people standing at one side, then you'll have to guess an 'in-the-middle' object to focus on with spot AF to try to get as many things in focus as possible. Or you can use auto-11 and hope the camera gets it right. Increase the DOF by stopping down the aperture, use wide angle, and use an external flash.
    I don't subsidize marketing campaigns.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •