# Set number of digits after decimal separator

How can I specify the amount of digits after the decimal separator in output without limiting the total number of digits?

Simple question, but I could not find the answer anywhere. I did find SetPrecision. However, that let's me specify the amount of digits in total, but I am looking for a way to specify the number of digits after the decimal separator.

NumberForm[f, {∞, n}]

with n being the number of digits beyond the decimal separator