The Canon RF 800mm F11 IS STM is a very similar lens to the 600mm, but it’s a little bigger, a little heavier and features a little more glass (11 elements in eight groups, as opposed to ten elements in seven groups for the 600mm).
Bigger and heavier (but still compact)
The 800mm is 35% heavier than the 600mm, weighing in at 1260 g (2.77 lbs). At 282mm (11.1 in) when stowed in its collapsed position, it’s about the same length as the 600mm is when extended. When the 800mm is extended to its shooting position, overall length increases to 352mm (13.8 in). That’s longer than a mirror lens would be, but very compact for a conventional 800mm.
Larger filter ring, longer minimum focus
The general ‘upsizing’ of the 800mm compared to the 600mm extends to the filter ring, which is a less traditional (and less convenient) 95mm. The IS system in the 800mm is only rated to four stops, too, compared to five in the 600mm (rated as per CIPA, measured on an EOS R body). The minimum focus distance is longer, too, at 6m compared to 4.5m.
All of this probably makes the 600mm slightly more practical for most photographers, but there’s no doubt that 800mm can itch some places that 600mm can’t quite scratch. We suspect that both lenses will be a hit with fans of bird photography.
The RF600mm F11 IS STM and RF800mm F11 IS STM lenses are scheduled to be available at the end of July 2020 for an estimated retail price of R14 699 and R19 299, respectively.