When I bought my Canon 10D way back when, I found that I needed to turn off all the focusing

points, except the centre, in order to achieve the right results. Otherwise the main focus could

be on some peripheral point of the composition.

Since I up graded to the 40D, almost a year ago I have found that the multiple focus points

give a much better chance of correct focus, until now..........

This was one of a number of shots taken at a party. Not very good light so the 17-85mm lens

is at maximum aperture, but I am not sure that explains the software decision to make the main

focus the man on the right, rather that the more centrally placed lady.

Any suggestions?

For the other Canon owners: How do you set up your focus points?

Thanks in advance.

mmmm........I switch off all but the centre focusing point as you seem to do. THEN, I set my custom functions to enable the "*" button to lock focus on a given spot when pressed. On my EOS 5D it's c/fn 04>1. I also (except with telephoto long lenses) always use "one shot" as opposed to A1 Focus/A1 Servo.

I then (when using a zoom) zoom in on the area I wish to focus on, lock the focus with "*", zoom out to compose and shoot. The shutter button evaluates exposure.

In your case I suspect you've activated A1 Focus/A1 Servo and the lens has focused on the near subject because you (possibly) half depressed the shutter button and it's assumed this is your focus point (assuming further you kept the shutter half depressed).

Hope that makes sense, conversely, use manual focus. Zoom in, focus, zoom out and shoot.

p.s. If the lights low I suggest you up the iso and avail yourself of a greater range of f stops. In the case you've shown I would be looking at iso 500 and c. f8

Then again, as you know from the past, I would have used flash and none of this would apply!

Let me know how you get on - good luck

I find that allowing the camera to choose from the multiple focus points option is never reliable enough. As The Vulcan says, it will pick the closest, or maybe the point with best contrast, you never know.

Use a single focus point. Set up the camera so you can move between points with the joystick; then you can select the appropriate focus point quickly. If there is no focus point exactly where you want it, select the nearest focus point, move the camera so the focus point is over the area you which to acquire focus, hold the shutter half way so focus is acquired; and then move the camera back for the correct framing while keeping your camera half way on the shutter release. Then take the shot.

I never, ever use AI Focus. I use AI servo for moving targets, typically sports shooting, and "One Shot" for everything else.

I think the above is pretty much the same as what The Vulcan is recommending.

Thanks guys.

Using the single point then reframing is the way I always did it with the old 10D,

I was hoping that the 40D would have acquired more "intelligence".

Apparently not