So you want your iPhone to be easier to handle while taking photos with it? A big red camera button will definitely help. This POPA red camera button will make more sense for iPhone running lower than the iOS 5 which you definitely need a button for a quick press to take picture.
Of course, you can use it with your iPhone running iOS 5 and above, as a big red button is more prominent for clicking than clicking the “volume up” button.
The big red button needs to work with its own picture taking app which can be downloaded for FREE from Apple app store. The red button costs $75 which sounds too deep. If you desperately want a big red button and a better grip for taking pictures, you wouldn’t mind to pay for it. You can grab it from Amazon