I've been experimenting with various lenses for capturing puffins in flight on Skomer Island this season. This image was shot with the D810 and the new Nikkor 300mm F4 fresnel lens which is wonderfully short, light and easy to maneuver. It is a composite of five shots from a sequence of 6 of which one was out of focus and has been omitted. The resulting image is 834MB! The Nikon 70-200mm VR II gives a might higher hit rate of in focus images but the size of the puffin is correspondingly smaller. A 300mm on a full frame camera is the best option for capturing frame-filling shots. A 70-200mm on a cropped-sensor would be the best option.