Is this necessary? screen quetions

[Smithy]

I've read a little online about people using led's for back light but is that necessary?
I understand it's to con severe power but how much power dose it really con severe?
also, is there analogue to digital converter's?

[Soop]

As for how much power it saves... It depends what you're replacing.

For instance, the Nomad screen mod saves loads of power, because the original light source was some kind of gas tube, which is really inefficient. Generally LEDs are very efficient.