I post too Much on Here!!
- Jul 21, 2010
Sorry, but it’s not reasonable at all. First, the RF 24-105 wasn’t significantly shorter, and the RF 50/1.2 is a helluva lot bigger (both of which were discussed above).Compare the EF70-200 f/2.8L to the preview of its RF equivalent, which stands about 1/3 shorter. Same goes for the RF 24-105 f/4.0L vs its EF counterpart. I think it's reasonable to expect that an RF 100-400 - if they go with the same basic performance specifications - will follow that same pattern.
But for the 70-200 you’re missing a key point — the RF 70-200/2.8 is substantially shorter than the EF version because the RF lens is an extending design, an inner barrel extends as you zoom, just like the RF/EF 24-105 , the EF 70-300L, and many other zoom lenses. The EF 70-200 lenses are all fixed length, non-extending lenses. The reason the RF lens is shorter is that extending design — when zoomed to 200mm, the RF lens is actually a bit longer than the EF 70-200/2.8 IS II, such that the sensor-to-front-element distance is about the same for RF and EF.
The EF 100-400 already has an extending design (that was the point @degos made), so there’s no reason to think an RF version will be shorter (but good reason to think it’ll be 20-25mm longer).