So called, no-limit-step-up-down gadget.
It supports from 40.5mm to 82mm in either way, up and down.
There is even bigger set which starts from 26mm. (What camera lens use 26mm filter, by the way???)
What it is for?
I have ND 1000 for ‘long exposure’ photo in 77mm diameter. But I don’t have 20-35mm Nikkor any longer that uses this size of the filter.
And I don’t expect any chance to use this size filter for Sony A7m2 in future…
Also I have Cokin square filter box. but I found useless for ‘long exposure’ simple because no ND 1000 filter available in 100mm square size.
But Cokin filter box has another (unintended) function which is lens hood for large filters like 77mm.
In long exposure photo, proper hood to block ambient light is upmost important matter…
Yes, I am preparing long exposure shooting, for coming holidays in next week. (Huhuan mountain & Cingjin farm area)