I would like to thank you all for the replies. It's valuable information for me as I am a beginner. I will try to test everything you said and also buy a beginners guide!
>Are you using a good AF target? >
How you define a good AF target?
>Is your subject static or moving? >
I shoot mostly static objects.
>What is the ambient light level when you experience the >problem? > >If the light level is very low, do you have the AF Assist light >On?
Usually I am experiencing the problem in low light conditions and as you correctly predicted I have had the AF Assist off, I will try to shoot with AF assist on. When shooting in broad daylight usually I manage to focus but not always. I am thinking that it has to do with what you said earlier on about a good AF target. Again I would like to thank you all for the replies. I will shoot more and more and I will report back my adventures