You can download the app directly to your device through the Nokia Collection in the Windows Phone Marketplace.
The Camera Extras apps which integrates into the camera on your device brings four new features to your device camera, which are Self Timer, Panorama, Active Shot and Smart Group Shot.
Self timer allows you to set a ten second timer on your camera before the photo is taken. Auto focus takes effect when there is two seconds left so you have enough time to join your group for the photo.
The Panorama feature you can pan and stich several photos together, The panorama feature is not as quick as Nokia’s Creative Studio app to stich the pictures together but a welcome feature to the camera.
Acton shot takes 8 consecutive photos, allowing you can choose which to keep and which to delete. Autofocus is not active in this mode.
Smart Group shot takes five pictures, and you can choose faces between the five photos to choose your favorite.
Watch the camera extras in action in the following video demo.
source – The Nokia Blog