OK, OK.
I know that we are dealing with hypotheticals but lets go with some assumptions:
- Image quality is somewhere 10-15% either side of the 24-70 f/2.8L II. I have to say this because of the variation in the 24-70L II. It is possible that a single 24-70L f/4 IS could be both 10% better and worse than the 24-70mm f/2.8L.
- In particular the distortion from the 24-105 is eased, especially at the wide end
- The lens has 4-5 stop IS
I know that we are dealing with hypotheticals but lets go with some assumptions:
- Image quality is somewhere 10-15% either side of the 24-70 f/2.8L II. I have to say this because of the variation in the 24-70L II. It is possible that a single 24-70L f/4 IS could be both 10% better and worse than the 24-70mm f/2.8L.
- In particular the distortion from the 24-105 is eased, especially at the wide end
- The lens has 4-5 stop IS