The Sony a9 is maturing nicely with 3rd parties and Sony stepping up to ensure action photographers are covered. The Sony FE 100-400mm F4.5–5.6 GM OSS is the gold standard for photographers looking for tracking speed but adapted Sigma and Canon glass both perform very well today. Sigma has a slight advantage because the Sony a9 sees the lens like it is a native FE lens with the use of the MC-11 so the only real drawback is a slight lack of speed.
Join our Sony a9 Owners Group, also follow the Sony a9 Page to get more tailored news on Facebook and follow SonyAddict on Facebook and Twitter.
Sony a9 Action Shooting Kit: B&H Photo / Amazon / Adorama
Sony a9: B&H Photo / Amazon / Adorama
Sony FE 100-400mm F4.5–5.6 GM OSS:B&H Photo / Amazon / Adorama
Sigma MC-11: B&H Photo / Amazon / Adorama
Metabones Smart Adapter V: B&H Photo / Amazon / Adorama