Can't focus

I was trying to take a picture this afternoon in Av mode when I noticed that I couldn't get the subject in focus. I tried autofocus which didn't focus as well as manual focus. Neither of which gave a clear image. What caused this and how can I fix it?

check your dioptric and make sure you have set it correctly for your eyes.

How can I check that?

Check the distance between the cam and subject, you could be too close for the lens to focus.

No, I was 2 feet away.

Maybe it was too dark. But that shouldn't be a problem in manual, hmm.

What lens were you using? For some lenses, 2 ft. is too close for focusing.

That's what I was thinking too. 2 feet = 60cm, that's fairly close.

I was just using the regular lens that came with the 350D, an 18-55mm lens. I think that's the lens.

I have had the same problem when trying to take a landscape shot in the AV mode on the 18-55mm lens couldn't find a point of focus? It just wandered up and down and then gave up! Anyone have any ideas? The lens went in for a service and hasn't been the same IMHO. Maybe I should just invest in some new kenses and just forget about this one??

i am having a similar problem and wondering if i needed to adjust my dioptric focus. here's my issue: should i get the squares or the circles inside the squares to be sharp? or both?
it's making me nuts because i can't take a sharp portrait anymore.
the subject still looks fuzzy even though the background is nice and blurred out.

would having a improperly adjusted dipotric effect the shaprness of the pic?

Not in autofocus.

Mark

but in manual focus it will mess it up, yes?
sorry if i am stating the obvious but i feel like i am starting all over again, now that i have this digital camera vs. the film camera!

Yes, it can do. If the dioptric adjustment is set wrongly, and you're using manual focus, then it might seem to you that the picture is focussed properly when in fact it isn't. Or vice versa. Page 42 of your 350D's manual shows you how to set the dioptric adjustment, and it shows you where the "default" setting is (i.e. the right setting if your vision is good, or if you wear contact lenses or glasses when you take photos).

If you want to adjust the dioptric setting, the easiest way is probably to manually focus on infinity, look at a distant object, and tweak the dioptric until the subject looks sharp to you.

If you're having difficulty focussing, posting some sample pictures here - and telling us exactly what you did - would help.