the follow-up to the RF 28-70mm f/2L USM will be 24mm at the wide-end and still trim significant weight off the current lens.
I am wondering how much weight Canon can trim from the existing lens. Sonys offering comes in at 918gr and is about 500 gr (512 gr to be exact) less than Canons offering. It would be nice to have a F2 zoom <1kg. But if Canon is adding 4mm at the wide end, I am figuring it'll be (hopefully only slightly) above 1 kg.
I´d hope for the lightest version possible, even it means starting at 28mm yet again. But I've read that a lot of people, especially event photographers, did actually hold back on purchasing this lens because it wasn't wide enough. I don´t know if it is the usual forum cry and internet talk or if it is a real concern.
I figured there might be another reason why Canon wants to offer a 24-70mm F2: I could imagine they'll one day offer a F2 UWA zoom as part of a trinity. If the UWA zoom only has to go to 24mm, it could make it easier to design and built it. Or they could go a bit wider, let´s say starting at 14mm instead of 16mm. A 14-24mm F2 would sound like a very nice lens. Plus, 16-28mm is kind of already taken, although it is f2.8. Whatever Canon decided to do (if they ever) I think there could be several great design choices:
RF 12-24mm F2 --> as wide as possible, even it is heavy?
RF 14-24mm F2 --> best compromise?
RF 16-24mm F2 --> as compact as possible while maintaining F2?
Anyhow, I hope going to 24mm is related to a UWA zoom and that'll weigh less than 1 kg!