Fig. 10: One of the tree swans after putting its head under water for searching food. It is a test shot with my used bought Nikkor 300mm f/2.8 and Nikon TC-20E II teleconverter. There's very little depth of focus when it is fully open. — EXIF: Nikon D3; Δt=1/1250 s; f=600 mm; f/5.6; ISO 200; 2018-04-27 9:45:36
