clouds problem

in our music video we wanted to include a shot of the clouds and fast forward the shots to imply that time is movie on or going past emphasising the idea of the character reminising into the past.
We set up at a camera outside our classroom with the lense pointing up to the sky, it wasnt a very windy day so the clouds didnt move as fast naturally to see the different when looking back onto the clip. We filmed this for half an hour and thought we had enough footage to use the effect we want to use on the video. Unfortunatley when looking back on the footage on the movie maker programme the video kept moving in and out due to the focus- as there wasnt anything to focusing on as it was just clouds the camera kept moving in and out to try find an object to focus on. When doing this next we need to take the focus off the camera so it doesnt automatically try and find an object to look onto, and also finding a windy day to make sure the clouds move enough so their is enough to fast forward and create the effect we are looking for the outcome.