The A Series filter holder and filters fit all 35mm SLR camera lenses with 36 thru 62mm diameter filter threads and Hasselblad (R) mount. A Series Filters require the use of the A Series Filter Holder. Fog Filters. These filters are available in two different densities and have a misty graduated area. The fog or mist effect (filter 150 and 151) is more pronounced with more distant objects while the foreground remains sharp and clear. These filters can be combined with Cokin Graduated and Sunset filters. Vertical adjustments in the filter holder provides a continuous graduation of sharpness between the near and far planes.