Handy screen trick?

[sphoenix]

I stumbled upon this accidentally on my dad's iPhone 3GS, it doesn't work on my original iPhone though.

Double tap the lock/home screen with 3 fingers to 'magnify' the screen and still use functions. Is this known?

 

[Watabou]

Yeah, it's known. It's a zoom functionality designed for accessibility. I think it only works on the 3GS and the iP4.