Good camera app that focuses?

I have an iPod touch (4th generation) and I like to edit photos on there and post them to my Instagram account. The quality of the iPod touch 4 camera compared to the iPod touch 5 is ridiculous. The 5th generation focuses and slightly blurs the background. The iPhone 5 and 4/4S also do that. I'd love to know of any apps that can do that, so do any of you know any good ones?

Phone cameras can never match real cameras because a real camera takes a large lens to be able to zoom (not digital zoom which is worthless).