The EF 24-105/4L MkI was a good size, but pretty soft. (I had it but switched to something else for discerning shots.) The MkII was substantially sharper, but bigger.
The RF 24-105/4L has the EF MkI size with the MkII image quality. It's quite compelling, but the game has moved on substantially. The 100-500 (at least at 100 and 135 where I've tested it) is modern-prime-lens sharp (if not quite the 100Mac or 135/1.8) and the RF 24-105 is not that good.
I've argued *** that pros now should be using f/4 trinity not f/2.8, but the slight softness of the 24-105 is the one reason I'm wrong in that.
The RF 24-105 has been on sale 4 years or something now, and if any lens would make sense to make a MkII out of it might be this.
Just as with the EF, the MkII could be larger and a little sharper, so the original would continue to be an interesting lens to own and not take a beating in the secondary market.
As a bonus, they might even downgrade the IS in it to be merely nominal or even absent. I think that the lens formula may well be simpler, and/or sharper, and/or lighter or smaller if it didn't have to do IS duty. My own tests of the RF135mm vs. EF135 with IBIS only (see the 135mm SHOOTOUT thread on the lens forum) suggest the in-lens IS may only be bringing 1-1.5 stops, if that.
*** In the old days, we needed f/2.8 trinity because:
- Autofocus wouldn't work well with less than f/2.8 (depending on the model, fewer sensors or vertical lines would stop working I recall)
- Viewfinder brightness hinged on f/stop
- we had such soft film images that masked the lost DOF from f/2.8: when even the sharpest details were pretty fuzzy, we couldn't see the loss from DOF un-focus until it was more un-focused
- given a choice between huge grain and a bit of lost DOF from large aperture, we'd have preferred less grain and shallow DOF--or at least preferred the OPTION of choosing it
- without IS and IBIS same story: hand-holding 50mm at ISO 800 and 1/30 and f/2.8 was already pushing it in regular night interiors. Going to 1/15 or ISO 1600 would be abyssmal
- without photoshop etc., if we wanted a subject to pop out of the background we HAD to shoot it that way. There was no post-processing we could easily do.
- and all the above in the context where we could only shoot 36 exposures before serious down-time. That means especially, we couldn't do that 50mm at ISO 800 and 1/15 ten times and assume one would be usable. Not if we wanted to shoot more than about three shots that roll.
So, the trinity zooms were f/2.8 even if that meant we initially had 20-200 coverage instead of greater.
Today all those points are moot or even reversed:
- autofocus and viewfinder brightness have nothing to do with aperture
- sensors are bleeding sharp even at ISO 16000 so bad DOF is in your face
- IS, IBIS let us take 1 sec shots at 135mm with the 100-500 and count on 90% of the shots being fine for less than fine art use.
- the photo as shot is only the beginning of the image; we can edit as much as we want afterwards.
For these reasons, I use and recommend the f/4 trinity. But yeah, the 24-105/4LIS could be a LITTLE sharper...
