Last night, while working on the VBS (Vacation Bible School) closing program video, I figured out an easy way to do a camera flash effect in iMovie. It's pretty simple. A Wash-In transition is used. Wash-In for those who don't know is a transition that fades in from white. So, put the photo where you want it in your movie, and then add a wash-in transition before the photo. I use a length of 4 frames for the transition. Then add a sound-effect to one of the audio tracks. Works great, and when used in moderation can add some spice to your videos.