I would like to focus an iPhone 5s' torch light into a beam with an angle of around 5 degrees or smaller (hopefully). Is this easily doable with a single lens?
I'm hoping to buy a lens and attach it in front of the iPhone (by 3D-printing a custom case). I just don't know which lens I should get.
This is for an artistic project. It doesn't have to be very precise. Since I will be using around 75 iPhones, I'm hoping the lens to be fairly cheap and easy to get in bulk.
Any input is appreciated. Thank you so much!