I shoot concerts and I do this mostly with my DVX200 (when not multicam), for example - this one. DVX200 lens has very smooth zoom and a good range. But I'd like to use GH5s with similar kind of lens. Which one would be close to DVX200's?
I guess I'd need a good follow focus system too.
No, there is not a comparable lens for the GH5s. Still camera lenses are most always a shorter range like 2-3x and do not have any motorized servo mechanisms. Many people want Panasonic to upgrade the DVC200 with the GH5s sensor. Maybe that will happen someday.
The closest lens that I can think of would be the Olympus 12-100mm f/4 IS PRO Lens, which is sharp, has a constant F-stop, and covers a fair bit of the DVX200 range. ( not sure if it's parfocal or not )
For zoom range the best option may be the 14-140 although its very dark. Considering how good higher ISO is with the GH5S however I think its probably comparable to the f2.8 to f4.5 of the DVX200 anyway. Even if you keep the 14-140 at a constant f5.6 thats more like a f2.8 compared to a non dual native ISO camera.
Unfortunately no m43 DSLR lens has a power zoom except for a couple of Panasonic slow zooms. https://www.bhphotovideo.com/c/product/818956-REG/Panasonic_H_PS45175K_Lumix_G_X_Vario.html
very slow at f5.6 but again the GH5S helps a lot and f5.6 is no longer a death sentence on m43 with the GH5S. Basically dual native is just shy of 3 stops better making a f5.6 act like a f2.2 lens when compared to a camera like the DVX200. Since the DVX200 starts at f2.8 I think its perfectly acceptable to use f5.6 on the GH5S for very good results. Not to mention f5.6 is a heck of a lot easier to focus with in many of the shoots that require a power zoom. Limited range but if you have two cameras its not unrealistic to just keep the DVX200 for wide shots and keep the GH5S as a zoomed in camera or flip them around. Personally I would use the DVX200 with its larger zoom range as the one camera that can get any FOV and treat the GH5S as the closeup secondary camera.
It's a bummer Panasonic gave up on the power zoom lenses. I think if they weren't stuck at f5.6 they might have been better received.
A large sensor camera set always the right tool for every job. If you really need a long zoom coverage stay with a 1/3 - 1/2 Inch sensor camera with a large zoom. Spice it up with say a gh5 and an 85mm 1.4 lens for signature shots.