Compare the EF 300/2.8 II (2011) to the RF 100-300/2.8 (2023). The latter is 30% longer and 13% heavier. Apply that to the EF 500/4 II (2011), and you get a lens that's 115 mm longer and 400 g heavier, making it a bit larger and heavier than the RF 600/4. So even if Canon does 'better' it's likely to be similar in size and weight to the current 600/4.
If Canon released a 300mm/2.8 prime today it would be similar in size to what Sony offers (if they wanted to sell any). Meaning it would weigh approx 3lbs. the EF 300/2.8 II is over 5lbs. They went with a bigger, heavier zoom rather than a more compact prime. A prime f/2.8 300mm released in 2024 would be expected to weigh considerably less than the 100-300mm zoom that Canon released a couple of years ago. Something like the 300mm that Sony released.
Sure. The 300/2.8 II never got the weight loss treatment Canon gave to the 400/2.8 and 600/4.
Why? Has physics changed in the intervening 10 years? I'm sure they will shave off as much weight as they can, but just because some people have unrealistic expectations doesn't mean they can work miracles. PS this rumoured lens does indeed go to 500mm, as you demand.
I do like your idea of a new Canon RF 500mm f/4.5 prime that weighs around 4 lbs. However unrealistic that is in the real world.
I can pretend the new lens will be much lighter in weight, for a few months more. Give me that much at least.
The Sigma 500mm f5.6 lens weighs 1365 or 1370 gram (depending on the mount). A 200-500 f4 zoom has a much larger front element, likely more glass inside the lens because it is a zoom lens, an image stabilizer and the weight of the zoom mechanism. And it will be built like a Canon L lens.
