The Heliopan 39mm #5 Light Yellow Filter is a basic contrast filter, primarily for use with black and white film, that is primarily used as a haze filter to subtly darken blue tones and increase overall contrast. There is an approximate 1.5-2x filter factor with this filter, requiring an increase of 0.5 to 1 stop for normal exposure.
The front and rear surfaces of the filter both feature a single anti-reflection coating. Each coating helps to increase light transmission by reducing reflections, scattered light, and ghosting. Additionally, they offer protection to the filter substrate while helping to keep the glass clean for longer than uncoated glass.
This Heliopan filter is constructed from Schott glass for increased optical clarity and color fidelity. It features a brass filter ring for durability as well as jamming prevention.