I’ve been doing this math as well. Seems the best way forward is to pick one RF lens for now and rely on the adapter for others, and slowly upgrade each lens over time. So this begs the question, which has priority? An argument for each: (just within the trinity)My small math exercise (in GBP):
I don't doubt that R with new trinity will be great. But will it be £3.5k greater than existing setup? Considering that my trinity is probably worth less than 2k (16-35/f4, 70-200/2.8 Mk.II and Tamron 24-70/2.8 G1), the upgrade path will be ~ £5.5k. Will it be worth it for enthusiast? I don't think so.
- Cost of R ~ 2k
- Estimated cost of new trinity ~ 7k
- Estimated value of old 5D IV ~1.5k
- Estimated value of old trinity (Mk.III and 24-70Mk. II) ~ 4k
Adapter makes it more affordable because I can still use existing EF lenses but my motivation to upgrade would be lenses, not the camera.
EF 70-200 2.8 II + the adapter will be a monster compared to the new compact RF edition. Also you can likely carry a smaller bag with the new one if it fits vertically. If image quality is equal most will be happy, so advantage here is mostly size weighed against frequency of use.
RF 24-70 f2.8 IS: advantage here is obviously IS. If the new R body has IBIS this will be less of a factor. But for me, I think this consideration is lower on the list. Again, am assuming image quality is about equal.
RF 15-35 f2.8 IS: I think this one will be very popular for video users, but also may be the perfection of the genre of wide angle zoom. I’ve personally never owned a wide angle zoom in this range so maybe I don’t know what I’m missing, but for me this will be a tough call because the EF f/4 version will be so much cheaper in exchange for one stop, and usable for many of the applications such as landscape etc.
So personally my upgrade path will be RF 70-200, RF 24-70 and then maybe the 15-35, but then again maybe the EF f/4 for that.
That’s just of the trinity. But I think looking at all the RF lenses my upgrade path would look like this:
RF 70-200 f/2.8
RF 24-70 f2.8
If there is a RF 35 1.4 or faster that would definitely go in the list as well