I probably won’t though for stills for a couple of reasons.
First one is it can’t really replace my current line up of; 20-40, 28-75, 70-180.
It’s a near perfect line up for me with the 28-75 being my all day workhorse, the 70-180 being my ceremony, speeches and couple lens, with the 20-40 being my after dark dance floor lens, so it’s not like I am continually lens swapping all day long, just at a certain points.
Could I swap all 3 for the 28-105? Maybe, but with compromises at both ends plus having a lens which yes, does weigh less than all 3 combined, but individually makes for a relatively heavy unit with the Sony A7RV compounded further because I’d want to swap my baseplate for a battery grip.
I think the system I have is a better one.
For video though, yes. The compact and lightweight 28-70 has been my sole workhorse now for 2 seasons, but with a criticism.
Shooting 4k 50p last year, it was perfectly long enough at 105 equiv but too tight at 42 equiv.
This year shooting 6k 30p, it’s plenty wide enough at 28, but 70 is a bit short for my outdoor needs, which is about 70% of any job.
28-105 constant aperture f2.8 is both of the above use cases solved immediately so this lens is a no-brainer really for next year.
I had the Leica 24-90 last year but too big, too heavy and not constant aperture. It was a great photo lens but less so for video.
The weight of the 28-105 is just within my self-imposed limits and the only thing I do not like is the external zoom, but hey ho.
The next thing I’d like to see is Sigma make a sibling to the 28-45 f1.8. That WOULD change the game for me, for stills at least.
The 28-45 for indoor work paired with something around 50-100 f1.8, also with internal zoom, on a 60+mp sensor body and that’s it, I’m done for the remainder of my career, whether that be on my current A7RV, or on a potential future Lumix S2R.
Ideally, an S2R so it’s all within one single system, but either way I would not be too fussy as both options would be unbelievably good.