We had the chance to try the new Sony FE 100-400mm zoom lens on the Sony FS5, with the 1.4x teleconverter. The zoom is full frame, but the FS5 is 35mm, so we get a crop on that. The maximum zoom combined is around 750mm.
We recorded in 4K RAW to the Atomos Shogun Inferno and mastered to 4k with LUTs applied. The camera reported a f6.3-8 range. No sharpening was applied in post. Autofocus worked fine.
This short segment contains long range close-ups, including buildings and landscape over 2km away, where atmospheric distortion can be seen, as well as rain showers. We also caught wildlife on a Gymea lily, which is a flowering plant in the family, Doryanthaceae, with a flowering spike 4-6 metres off the ground.
Overall, the quality of the images are pretty good, with a reasonable depth of field for wildlife. No obvious vignetting. Sharpness and contrast were also pretty good considering the amount of glass involved.