Unless the firmware is different to the 4kt and it's interface the fact you can enter shutter speed in ms, whilst a pain for beginners on the one hand, is also a god send when trying to uncouple yourself from set multiples to avoid rolling shutter. With set shutter speeds you're locked to common values / multiples. At least with ms you can experiment with differing values eg if looking for 4ms you could also try 3ms or 5 ms. I can't remember if the interface allows decimals but if it does, you could try for example 3.5 or 4.5. Maybe you can hit on a shutter speed that gives you the speed you need whilst minimising rolling shutter effect this way by departing from those common values. I personally use 4ms on my cameras and they're immune to my led lights. My neighbours internal garage light is fluorescent however, and this does trigger rolling shutter if they go into the garage and switch it on with 4ms shutter. It's minimal though and not often on, only minutes at a time, so I live with it.
