You do not need to be a professional photographer, nor do you need any expensive special equipment to get great results.
Here is the best way to take digital photos of movie posters:
Use a 5 mega pixel or better camera. Natural light is the key. Do it outside, on a nice sunny day, not on a windy day. Do it in a place where you won’t be disturbed and away from your pets. Place the poster on a sheet or rug on the ground IN THE SHADE, NOT IN DIRECT SUNLIGHT. If it needs it, put books or something on the corners of the poster to hold it down flat. Try not to cover any important details like NSS info. or any flaws the poster may have. Set the camera on a “CLOUDY DAY” setting with NO FLASH. Hold the camera directly over the middle of the poster about 4 to 5 feet from it and take the pictures. Hold the camera closer if you need close ups of a certain area. They should come out perfect this way.
If they need a little editing, you can crop them, adjust brightness/contrast, and resize them in a photo editing software program. We use Paint Shop Pro.