Best lens for low light

[mereb_ed]

(New to Portraits): What’s the Best Lens for Low Light?

[p4pictures]

It would help to have a little more information as to the camera model you are using and also the distance from camera to subject to be able to give accurate advice. 

in broad terms, a fast aperture lens gets more light into the camera so look for a lens that has f/2.8, f/2, f/1.4 aperture as it’s maximum. This helps you have a reasonable shutter speed to avoid movement of the subject from causing blurred results. In general for most people who are static you will need 1/125th as a minimum shutter speed. 

Lens focal length is usually a medium telephoto to flatten facial features for more flattering results. Something like 85mm to 100mm is a good choice on a full frame camera. 

[rs-eos]

For portraits (assuming headshots or half-body), two lenses come to mind: EF/RF 85 mm f/1.2 and RF 135mm f/1.8 (EF 135mm f/2)