Future Lens (changes highlighted in red)EF 135mm f/1.8L USM with 4-stops of ISEF 400mm f/5.6L USM with 4-stops of IS Current LensEF 600mm f/4L IS II USM
In 2003 I got myself a EF 17-40mm f/4L USM because it was the newest ultra wide zoom available. At the time I had no understanding of f-numbers. I am thankful I got this lens as the faster ultra wide was replaced by the EF 16-35mm f/2.8L II USM soon ...
