You want a "fast" lens. That's a lens with a wide aperture (low f-stop). The cheapest of those are prime (non-zooming) lenses. The cheapest of those are 59mm lenses. You can get f/1.8, f.1.4, f/1.2, and even f/1.0 versions. The lower the number, the more light the lens will gather. The price rises exponentially as well.