Model 138LLUC3. 138mm size (unthreaded drop-in style mounted for filter adapter ring or matte box). Retails originally for $322/each.
The Tiffen 138mm Mounted Low Light Ultra Contrast 3 Filter is a contrast control filter that is designed for cinematography. It can be applied to purposely increase detail within shadow regions while recording video under low-light conditions. By distributing ambient illumination to darker areas within a scene, this filter is also useful in helping to uniformly balance the tonal range among highlights and shadows. Overall contrast is reduced while flare and halation around highlights is purposely limited.
This filter has a grade of 3. Grades of 1, 2, and 4 are also available where this filter type's effect becomes approximately twice as strong with each grade number increase.
This filter is made using ColorCore technology, a process that involves laminating the filter substrate between 2 pieces of optical glass and grinding flat to a tolerance of 1/10,000th of an inch. No front or rear threads are included on this filter's ring, or mount, which is 138mm in diameter and designed for use in third-party or custom filter holders.