comments:
If you want to get into filmmaking with a iPhone, go for Beastgrip. I spend a lot of money buying cheaper stuff (cage, lenses, filters) and it was not worth it. Its collecting dust at the moment. I bought a Beastgrip cage, Beastgrip tele converter lens, and K&F VND filter. The K&F Nano-X series is not a top notch filter but really good.Beastgrip sells a universal cage (Beastgrip Pro cage) in which you can mount any smartphone and is cheaper than their metal cases for specific smartphones. https://beastgrip.com/products/beastgrip-pro If you buy a set of cheap Filter ring adapters. The 37mm - 43mm ring adapter fits on the lens mount of the Beastgrip Pro case and I advice to buy a minimal 77mm VND filter.I again started smaller and those are also rotting in a drawer..... https://www.amazon.com/Filter-Adapter-Concept-Camera-Stepping/dp/B00JL4HGAI?crid=2QPZ0ASM8HPNG&dib=eyJ2IjoiMSJ9.uDMIvxdF0n6opdmSoPO71Wsg5tlYYvaerI3Jnay3E8NbP3RIBbMd3gIUPBkbmjuqSKt2VDCM12lsY0NmyI1KeIaCn9ST6Fl1eFIuedpJ_IL2cy0nufg9e-F6z-t36evY_vGhkGBbmh5CiBlN3IoQ7w8ftVHGm1n1Fp8x7zVDnVxN4kASDbY2i_HiP6mAlLiJ4HzPB_hyRu5ogqOuPpPri40M24dnxtCu2s7gZmllwE0.7BSPd0tXiUUNB5GBUuNmlbLbQmdKOVlwnvrkBqTTWQk&dib_tag=se&keywords=filter%2Bring%2Badapters&qid=1782380247&sprefix=filter%2Bring%2Badapters%2Caps%2C209&sr=8-3&th=1 77mm is a widely used size for (photo) lenses and you can keep using it after years and years when you grow into filmaking. Unfortunately I now bought a Blackmagic camera with a zoom lens with 82mm filter screw thread so now my 77mm does not fit anymore and I have to buy a new one but I used my 77mm a long time. Beastgrip sells tele converter lenses and even Anamorphic lenses and the 77mm filter will fit them also.
Which body do you have? I don't mean to give a non-answer but a lot of the Olympus bodies do liveND which works pretty well. The k&f variable filters are great though, they definitely take things up a notch. they also make a step up ring kit, you can see some examples in their product photos. https://www.amazon.com/dp/B00JL4HGAI