Hi, Jochie.
Thank you for visiting Apple Support Communities.
You may find the information in this article helpful.
iOS 7 uses a parallax effect to create the perception of depth on your Home screen and elsewhere. When this feature is on, you may notice that your:
- Wallpaper, icons, and alerts shift slightly as you move your phone.
- When setting a wallpaper in Settings > Wallpapers & Brightness, the photo or image will be slightly zoomed and cannot be scaled to fit to the screen.
You can change this behavior by enabling Settings > General >Accessibility > Reduce Motion.
Note: If zoomed, you will need to rescale your wallpaper to fit to the screen.
iOS 7: How to reduce screen motion
http://support.apple.com/kb/HT5595
Cheers,
Jason H.