Cokin WA1T139 Series A Gradual FLD Filter

The Cokin WA1T139 Series A Gradual FLD filter is a rectangular resin filter designed to slide into the Cokin A Series holder system. Its graduated design applies fluorescent-to-daylight color correction across one half of the filter while leaving the other half clear, making it particularly effective for landscape compositions where fluorescent-lit structures or mixed lighting affects the sky while the foreground requires no correction. By sliding and rotating the filter within the holder, photographers can position the transition line precisely where the scene demands it.

As part of Cokin's long-established creative filter system, the A139 is stackable with other A Series filters for combined effects. The FLD correction works by counteracting the green spike common to fluorescent light sources, shifting tones back toward natural daylight balance. While digital white balance can handle uniform fluorescent casts, this graduated version addresses situations where only part of the scene is affected — something white balance alone cannot selectively correct. It is best suited for photographers who already own or plan to invest in the Cokin A Series holder ecosystem.