This is an Neutral Density Filter Kit with Low Profile Clamp-On-Locking-Ring adapter, designed to mount 4 1/2 inch filters included in the kit on a camera lens with a front diameter of 114mm such as the Zeiss CP.2 and Canon Cinema EOS Primes. Great for filtering lenses with no front threads and situations where a regular matte box would cause too much wind drag.
This kit includes three Neutral Density Filters used for Cinematography. It has a Neutral Density of 0.6 (2 stops), Neutral Density 0.9 (3 stops), and Neutral Density 1.2 (4 stops) and therefore reduces light transmission into the lens. A common use for these filters is to allow the use of larger apertures, reducing depth of field, to allow selective focus and rack focus.
*Note: The lever must be in the un-clamped (up) position prior to un-threading retaining ring.