Ah yeah, that's not a rule of course. But main point is to keep shutter low as possible. So ND filter is needed for doing this . By this way, wobble or jello minimized, it is actually masked. A solution. By the way, i get best result on 4K, 30...
... and if a uniform motion blur isn't a major concern & if a manually locked shutter speed feels too limited in changing exposure environments when videoing... you can use a auto shutter+ND as the ND filter slow down the shutter in general, not...
Update !
I was getting a noticeable wobble or jello effect when shooting in vertical mode, especially at 3x zoom. After trying various things, what finally fixed the issue was using an ND filter to properly control the shutter speed.
By...
Unfortunatelly, i replaced other one also with Aliexpress part and nothing changed. Still vertical videoas are wavy and horizontal ones are not even noticable. I replaced also propellers with newer ones. I gonna use ND filter to hide it by...