Canonwatch has come across an exciting new patent https://www.canonwatch.com/canon-pa...extender-1-4x-and-600mm-f-4-is-extender-1-4x/
The prospect of a 400mm f/4 with the TC is exciting for me anyway! The focal length is given as 392.58mm and the f = 4.12. It can be squeezed into just over a 95mm front element, which is close to what I measured for the EF 400mm f/4 DO II. The 600mm is not a DO lens.
The prospect of a 400mm f/4 with the TC is exciting for me anyway! The focal length is given as 392.58mm and the f = 4.12. It can be squeezed into just over a 95mm front element, which is close to what I measured for the EF 400mm f/4 DO II. The 600mm is not a DO lens.