Focus Points

[scott1120]

My camera (D50) has 5 focus points. I know how to use the different ones but I don't know what I would want to use them for. Does anybody have a good layman's definition? Any examples would definitely help. What does it give me if selecting say the left point in opposed to just re-aiming the camera in that direction?
I hope that was not too confusing.

[carrbowl]

Great question...looking forward to an answer

[CaptainTom]

One quick example:

vertical portraiture.
selecting the top focusing point instead of using the center and then recomposing allows you keep the "film plane" parallel to your subject at all times.
tilting the camera to focus, and then recomposing moves the focal plane a small amount. This could be critical in a shallow DOF situation. More critical the closer you are to the subject. (greater angle of incidence).

[huxley]

learning to use the focus points is easy. learning to use the focus points EFFECTIVELY is a different story. i focus my my points manually 90% of the time. what i like to do is figure out my composition, and how i want to frame my subject be, it horizontal or vertical. from there is where i decide where i want to focus on my subject. when using the focus points it is useful to keep in mind the rule of thirds.

i.e. say im takeing a picture of a hand. i frame the hand horizontally and am ready to focus. well do i want to focus on the thumb or pinky? if i have a small depth of field like f1.8 it will be an important decision. since the fingers are so far apart (and different legths) only one will be in focus. so picking the correct focus point is imperative. so its a little like deciding what you are going to reveal to the viewer. what will stay out of focus and what will be in detail? clear as mud? thought so.

[scott1120]

So, lets see if my mud is clear. I want to use focus points to make my composition without changing the "focal plane". To clarify you example of the hand; use a focus point on the say the thumb. If I move to point the camera at the thumb then I might lose the hand in the frame, right?

[kenw]

scott: basically, yes.

In landscapes, I might compose a pic to have a tree at the left side of the image, and want it to be the focus spot, allowing the remainer of the scene in the frame to be softly out of focus. By using the left spot, I can focus on the tree and frame the scene as I want all at the same time.

Or you might have 2 people side-by-side. The center focus spot would focus the lens on the wall 10 feet behind them since it is looking between both of them. Use either the right or left focus point on a face/chest and it will do what you want: focus on the people.

[huxley]

you are correct sir!

you could just let the camera think for you and let if focus but whats the fun in that? there are a lot of people that will tell you around here, learn to do EVERYTHING manually. from exposure, aperture, focus, and composition. learn your camera you learn to shoot.

[engstrom]

If you focus on the subject with the center autofocus point and then recompose the picture so that the subject is off to the side it will actually back focus. I'll attach a picture that illustrates the point.

[huxley]

NOT TRYING TO BE MEAN but is that thing doing its "business" on him? lol sorry couldnt resist.