I'm posting this here as it's the phone I have but this will work on ALL ATIV branded WP devices. Samsung have released their ATIV Camera app for WP8.1, I couldn't get it to work properly though as I suspect that I need updated firmware but it's a nice addition to their apps.
http://www.windowsphone.com/en-gb/store/app/ativ-camera/f222ba58-e134-486a-a146-6d28ef6f0083
http://www.windowsphone.com/en-gb/store/app/ativ-camera/f222ba58-e134-486a-a146-6d28ef6f0083