XUME 77mm Lens Adapter and Filter Holder Starter Kit

You attach the lens adapter to your lens and then attach the adapter ring to the filter, then the two attach via magnetism.

the ring measures 3.4mm thick. If you needed to store a magnetic ring and the filter inside, you may need to remove the foam.

The pro kit has double the amount of adapters and holders.

I have the 62 mm set and it is 15/64 in thickness. If you include the threads that go into the lens, it is 20/64 in thickness. (5.8 mm and 8.2 mm respectively)

Yes, you need a separate base of the appropriate size to mount on each lens diameter - unless you want to place a step-up ring (e.,g. 58mm -> 77mm) on the smaller diameter lenses. Then you could use a single 77mm base and standardize on 77mm holders and filters. Be aware that the accumulated thickness of adapter, holder, and filter significantly reduces the lens angle of view and will cause vignetting on all but long lenses. For that reason I have switched entirely to the Lee filter system for all filters, which I have used for years on large format cameras.Furthermore, the Xume magnets, while reasonably secure, can get knocked lose, sending a $200 polarizer crashing on the ground.

No one else makes this product. It i not an easy part to make. The availability of the various sizes is driven by the volume of sales predicted by the manufacturer.

Used the camera and lens with the UV filter above with and without the Tiffen Circular Polarizer and found the Circular Polarizer produces vignetting in the lower corners some more profuse depending on the orientation of the Circular Polarizer. Darker lower corners does mask the effect. Upper light corners had no vignetting.

It's moderately bad. I use it on that lens and it's not so bad with just a UV0 but you get significant vignetting at 16mm with a CPL. At the longer focal lengths it's fine.