I love Fujifilm cameras... have 3 of them: XE2 XT20 and XT4. Started getting hooked on BIF a year ago. Got the 100-400 but despite much practice, the keep rate is only about 50%. This really bugs me because the "keeper" are stunning...as the Osprey illustrates. Any help, advice, comments appreciated... (in the meantime shooting with D500 +200-500. Amazing BIF AF...keep rate 80%+