Hand held, Procapture mode, I was focused on the swallow, I could see the hoverfly, as soon as I saw the Swallow twitch I pressed the shutter, I was please the fly remained in focus!
OM-1 OM 150-400mm F4.5 TC
Focal Length (35 mm conversion) : 1000.0mm
Exposure mode : Manual exposure
ISO : 2000
Exposure compensation : 0.0 EV
Shutter : 1/4000 sec
F number : F5.6
ACR/PSCC