B+W's 60mm Star Cross Screen 684 4X Filter produces a 4-point star effect. The rays begin right at the light sources. They are very long and are most effective when they are not vertical and horizontal, but at an angle of approximately 45° to the vertical axis.
This filter is uncoated. Uncoated glass is usually found with special effects filters and acrylic filters, where coating is either an impossibility or would work against the effect the filter is trying to attain.
This filter uses the standard B+W F-Pro filter mount, which has a front accessory thread and is made of brass. Compared to the earlier standard mount introduced in 2001, the F-Pro mount has become thinner. Now it can be used with wide angle lenses, including most 24mm focal lengths on a full frame body, without vignetting. Another advantage of the F-Pro mount is its modified retaining ring, which is no longer threaded in from the front, but holds the filter glass in place from the back. When removing a filter or lens hood that has been screwed on too tight to the filter, the retaining ring is not at risk of loosening.
Note: diopters are mounted in the older mount due to glass thickness.