The 70-300 really is capable of amazing results. Shot at 300mm, F/5.6, ISO 1600, 1/400th, handheld with OIS.
In full transparency, I did run it through DxO PureRaw 3, just to denoise and sharpen. Lightroom is still crap for sharpening Fuji RAWs. That being said, it was damn sharp even without DxO. I only use it on images I plan to print large, to get as clean an image as possible.
A very cold and windy December morning, several years ago...
In case you were wondering why I didn't use a longer shutter speed to blur the water, this video will give you an idea of what the weather conditions were like that morning:
Winter Morning at Waterton Lake
X-T1XF10-24mmF4 R OIS lens10mmf/8.01/35s200 ISO0.0 EV