Gave up on the Sigma 150-600 I have. Dropped to either a 300 with a teleconverter or a 500. The prime lenses are so much sharper. I'm in the Nikon side of things....
Really been at it since 2018. 1223 on the life list. Fortunate to be able to afford international trips for birding. Live in Indiana, USA.
https://ebird.org/profile/MTA0NzE5MA