This is usually a physical fault with the phones camera, the phone should still be under warranty and as long as it hasnt been in any water the Nokia service centre should be able to repair this for you for free. If you do want to repair it yourself, you will need a T6 screwdriver and the Camera module.
Remove battert sim and memory card... Take the phone apart, remove 2 screws at back, then the front cover. Remove 4 screws around the screen, remove phones PCB with the screen (no need to remove the screen) flip the PCB over and the camera is there.
Check the camera is seated correctly and the phone hasnt been water damaged...
MobilePhoneFX.com, June 2008
