using filters on XF lenses

nixda wrote:

There is no manufacturer that furnishes all their lenses with the same diameter threads. Lens sizes are just too different.

You have three options: (a) get filters for each thread size you have; (b) decide on the largest thread size you can imagine using, get filters for that, and use step-up rings to make smaller lenses work with the larger filters. (c) settle on two or three main sizes, get filters for those, and use step-up rings to make smaller lenses work

I would try to define what it is exactly that you want to do with filters, get the 14mm and then experimentally determine what filter size you need. With such a wide lens the filters presumably will have to be quite large.