Here’s a Snowy Owl image from the Sony a9 II Camera body with the Sony FE 400mm f/2.8 G Master OSS Lens at 20,000 ISO. The details are remarkable! The key is to expose to the right (Keep the whites all the way to the right hand side of the histogram, but make sure they don’t touch) and try not to crop. This is a full frame image without noise reduction applied.
Snowy Owl (Bubo scandiacus, Harfang des neiges, SNOW) from my Winter Snowy Owl Photo Tour in Ontario, Canada. Image Copyright ©Christopher Dodds. Sony a9 II Camera body & Sony FE 400mm f/2.8 G Master OSS Lens ISO 20,000, f/2.8 @ 1/5,000s. Manual exposure.