Focus Points !

[Marshy]

This might be a stupid question but please understand i am trying hard to do my camera justice . Had 300D for about 3 weeks and i am starting to get my head around digital photography mainly due to you guys and the feedback the camera gives me but one thing i am struggling with is how the focus points work . I started using all the focus points but was finding what i wanted to focus on wasn,t necessarily so , all i use now is the centre square , is the whole screen focussed or just the lit squares ?

[Kennymc]

The idea of the focus points is that if your subject is not in the centre of the frame you can use one of those red squares to act as the focus point... Try placing three objects about 1 foot (30cm) behind each other than use the squares to focus on the one you want to be sharp using a large aperture like f/2.8,you will see the other two go out of focus... You can use them all at once and the camera will try and get all the points in focus by closing down the aperture and slowing down the shutter speed to compensate...

[Marshy]

The idea of the focus points is that if your subject is not in the centre of the frame you can use one of those red squares to act as the focus point... Try placing three objects about 1 foot (30cm) behind each other than use the squares to focus on the one you want to be sharp using a large aperture like f/2.8,you will see the other two go out of focus... You can use them all at once and the camera will try and get all the points in focus by closing down the aperture and slowing down the shutter speed to compensate...
Thanks for that Kenny , isn,t a large AV also intended for overall
focus ?

[Kennymc]

HERE (http://www.kennymc.com/html/basic_exposure.html) Large aperture = big hole = small f/stop number like f/1.8 = shallow depth of field, so a large aperture would show the difference in focus points off better than if you chose a small aperture = little hole = large f/stop number like f/22 because the depth of field may cover more than one of the subjects and you wouldn't see much difference... I hope you don't think I'm talking down to you as I don't know how advanced you are so have explained it as simply a possible.. I hope you are not offended... If you are a biginner you can find out more here on my site..
HERE (http://www.kennymc.com/html/basic_exposure.html)

[roanjohn]

When using all focus points to achieve focus, the camera will look for the closest subject to focus........unless the initial subject doen'st have enough contrast then it'll be drawn to the next most contrasty subject. And yes, only the lit squares will be in focus........if all square lights up, then all the subject within those squares will be focused.

Did I explain it right??

Ro1

[vinnyveez]

When using all focus points to achieve focus, the camera will look for the closest subject to focus........unless the initial subject doen'st have enough contrast then it'll be drawn to the next most contrasty subject. And yes, only the lit squares will be in focus........if all square lights up, then all the subject within those squares will be focused.

Did I explain it right??

Ro1

no. well yes but no. he is saying that he is using the center square only for focusing. what you are talking about is when all of the focus points are being used (all are red), then it goes as you say. when you use only 1 point (only 1 point is red), it will focus on whatever is at that 1 red point. like the first poster replied.