[sleaver]

Well I've had it for a couple of weeks now and really enjoying it, however I have a question.

A couple of times I have half depressed the shutter button and its taken quite a while to auto focus and then it wont take a photo. Is this a problem with it or is it normal and the camera's way of saying 'I can't focus on anything and don't ask me to take a photo with these settings'?

[Jitetsu]

This is a standard camera response. It'll hunt throughout it's entire range to get focus and when it fails it'll let you know in a subtle way (I think the way the focus points in the view finder flash (or don't)) and then it'll stop you taking a shot entirely. It's most common if you're trying to focus on something that's too close for the lens to handle or you've got the focus point set over some sky or cloud etc.

[Brammers]

There should be a way to change this. I use a different camera, and on mine it's called 'release priority' as opposed to 'AF priority'.

In AF priority mode it acts as you describe; if the camera can't confirm focus it won't take a picture. This was the first thing I turned off :P

In release priority the camera takes the picture when you tell it to.

Time to break out the manual Be aware that Canon might call it something else.

[senu]

The other easy thing to do is use Focus lock.. Focus on something easy in the same scene by depressing the shutter button halfway, Still keeping your finger on the button quickly recompose and take your shot.
Canons AF assist light is in the built-in flash so it helps if that is raised too
AF will not work in areas of very low light or (but especially in addition) very poor contrast( this may be lens dependent too)
or
Use manual Focus
Have you seen THIS?( check out lesson 4)

senu cheers for that link