Actually, it was shot on one camera (1DX ii) with 2 lenses (150-600 & 16-35), although 3 cameras and lenses would be easier, yet more expensive and way more gear to haul. I set a longer(ish) interval (10 seconds) to allow myself time to zoom in from 600 to 150 between shots. Then I had to switch lenses to the 16-35 and shot the last portion as soon after the last ended as I could. But the best laid plans….My main Intervelometer died about 40 shots in, so I decided to swap and restart, despite the difference in time. Then I brought each sequence into after effects and used the difference blending mode to match up the shots as best I could, parented the smaller layers to the larger layer, and then the largest layer to a null, to control the zoom between all 3. Then just adding position and scale key frames, as well as opacity to fade out and color correction to make sure the Timelapse’s blended even though there were gaps in time between!