Sometimes when a flash fires you you take a portrait, the light from the flash reflects off of the subjects retinas and causes what we refer to as red eye. It can be cured by simply having the subject look away from the camera so the light cannot reflect directly off the eyes. Although chances are, you may already have some photos like this from before you learned how to prevent it. It's super easy to do in Photoshop. In fact, I don't even have a handout made since it's so easy to do. Instead, watch this simple video!