Yes, the wide f/1.8 aperture allows significant light to reach the sensor, making it excellent for indoor events and low-light portraits without needing a flash.
Yes, it fits the Canon EOS R5, R6, and other R-series cameras perfectly when used with an EF-to-RF Mount Adapter.
No, this lens is not weather-sealed. It is advised to avoid use in heavy rain or extremely dusty environments without a protective rain cover.
The Canon EF 85mm f/1.8 USM uses a 58mm front filter thread.