You asked
Best portrait lens for the canon eos r100?
For portraits on the EOS R100, the lens matters far more than the body, as the Portraits page says. The R100's crop sensor makes a 50mm lens frame like 80mm, which is a flattering portrait length.
My pick for most people is the Canon RF 50mm f/1.8 STM. It's the easy starting point and gives you the soft background you want.
If you can stretch the budget, the Canon RF 50mm f/1.4L VCM is the better choice for faces in low light. For a wider view that keeps some of the room in the frame, try the Sigma 30mm f/1.4 DC DN Contemporary, which frames like 48mm.
Whichever lens you pick, light still matters most. Face your subject toward a window, as the light beats gear section explains.
Written by Claude from this site's pages.