Used Fotodiox Vizelex ND Throttle Mount Adapter with Built-In Variable ND Filter for Pentax 645 (P645) Lens to Nikon F-Mount (FX, DX) Camera

Fotodiox lens mount adapter with a built-in Variable ND filter. The ND Throttle opens up new creative possibilities, like long exposure and shallow depth of field, even in bright conditions. No more carrying around a camera bag full of ND filters. Built-in variable ND means easy and convenient image control over any lens that you attach - even wide angle lenses that don't work with front-mounted variable ND filters.

This is a manual adapter, so lens functions that rely on electronic communication with the camera body (autofocus, AE metering, image stabilization, etc.) will be disrupted.

Set your exposure manually or meter using your camera's Aperture Priority (stop-down) mode.

If your lens does not have a manual aperture control ring, it will stop down to its smallest f/stop by default.