camera focus on wrong subject ???

why does the camera focus to a close subject when I actually want to focus on distant object. I have to continually adjust the focus. Is there a way to stop the camera from eratic focusing.

I have digital rebel XT with sigma 3.5f 70-200mm zoom lens.

have you try to use a AF points manually?

Just manually select the focus point that you want. You also could just have center point as your default focus point and use the old focus, recompose,shoot method. Now, if you just shoot in Auto mode you can't select your focus points. You have to be in P, Av, or Tv.

There are two methods for autofocus to do what you want.

The first is to implant a transmitter in your brain that would communicate your wants to the camera. Usually this is accomplished by manual focus where your brain directs your hand to focus the camera where you want.

The second is to put sensors in the eyepiece of your camera that can determine what part of the frame your eye is looking at and then cause the camera to focus on that point. This feature is available on my EOS 3 film camera, but has not been included on any digital SLR yet. (I don't find it very useful anyway.)

For your digital SLR, you can set your camera to just use one AF point. I usually choose just the centre point, focus using that point and then recompose before taking the shot. If you have a fixed composition you may want to choose an off centre AF point that is over the point you want in focus.

Also, don't be a slave to autofocus. If it doesn't work immediately, focus manually instead of wasting time trying to get AF to work. That is the reason I will only buy Canon USM and Sigma HSM lenses that have full time manual focus override.

Sorry, but the 'do what I want' feature was not implemented in your camera. That will come in the future, when the camera has a wireless connection into our brains! The camera thinks that what is important in the photo is in the foreground, not the background...which is a reasonable assumption for it to make when your family is the foreground and Mt. St Helens is in the background. It has no way of knowing when someone else is in the foreground (not your family) and Mt. St Helens is really your object of interest.

As others have pointed out, you can make the CENTER your AF point; also you can set your Custom Function to put focusing on a button OTHER THAN the shutter button, so you can center on the real object of interest and prefocus on it with that button; then reframe the picture and press the shutter to shoot the picture without altering the focus.

Picard do you know how to select a single AF point rather than all six? You may also want to try AI Servo (just a thought). I don't know what your are photographing.

EXCELLENT suggestion!

I feel that a lot of the folks using modern cameras are "stuck" on the automation - both autofocus and auto exposure systems. If there were an "auto-composition" feature, that would be used heavily as well I am sure.

Learning to take over control of the camera should be a goal for all photographers.

Yeah, just as purchasing an L lens makes everyone a good photographer! Sharper junk is still junk, you can merely see it better.