If you’ve been using iOS 7 beta, you might have noticed a zooming effect when you try to set your pictures to your lockscreen or homescreen wallpaper. This feature/bug has been present in the last couple of betas and appears to be a “feature” in the gold/final version of iOS 7.
The good news? There are a couple options you have to set your wallpaper.
Enable Reduce Motion
To do this, go to Settings > General > Accessibility > Reduce Motion, set it to ON. This will turn off the feature that makes your wallpaper float when you tilt your screen (parallax). After changing this setting, you can set your wallpapers just like you did in iOS 6.
Take A Screenshot
The other option is to take a screenshot of the picture you want to use. Open it up in your Photos app, click on it to remove the toolbars, then take your screenshot using the Home button and the power button. From there, open the new screenshot and set that as your wallpaper (it’ll have black bars across the top and bottom but that’s okay).