Hi all, I am a newish photographer and new to TPF but your responses to posts I have viewed seem useful so am hoping some of you can help me. I have recently purchased my first SLR - a Canon EOS 400D and loving the quality of picture it is given me. In my desire to become more skilled I am undertaking a correspondence course on 'Beginning Photography'. Am getting my head around all the new language and I finally think i understand Av. One of my tasks is to explore shutter speed and to take 3 shots of a vehicle moving with different shutter speeds. The problem is that when taking with a fast shutter 1/1000 the image is clear and correct exposure but when reducing the speed down the image becomes extremely overexposed. I know i have to compensate with Av but really don't have a clue has to what to do to ensure i capture the images to show a variety of movement but at the correct exposure. Can any of you more experienced photographers please explain how to go about this? Much appreciated from down under in New Zealand.