A Heliopan 48mm FL-D Glass Filter is used when you wish to correct for the greenish tone that appears when shooting daylight film under general purpose fluorescent lighting.
This orange colored filter blocks the blue and blue-green portion of the visible spectrum up to approximately 520nm. It reduces the excessive sensitivity of color infrared films for this spectral range, helps avoid blue tint and differentiates colors more evenly.
Fluorescent lamps burn at many different temperatures and often require more demanding filtration for exact results. For specific filtration and professional use, it is strongly recommended that a color temperature meter be employed along with Color Correction filters (i.e.CC30M) when shooting under fluorescent lighting. This is the only proven way to achieve exact color correction.
Heliopan Lichtfilter-Technik of Munich, Germany has changed their black anodized brass filter rings on most Heliopan non-rotating filters to their "slim" mounts. These slim mounts are made of black anodized brass stock and have so little rim in front of the lens (5.4mm) that they will not vignette with lenses as short as 21mm.
Heliopan offers a wide selection of sizes, screw-in, series, bayonet, square and rectangular filters including digital, video, center weighted, graduated, wide angle, Kaesmann polarizers, drop-in polarizers, etc.
NOTE: The FL series of filters alone does not always guarantee 100% correct color balance when shooting under fluorescent lighting. They are general purpose filters intended for moderate correction and will not, by themselves, necessarily provide perfect color rendition.
An FL-W filter is used to balance daylight film under warm white or white type fluorescent lamps. An FL-B filter is used to correct the color balance when shooting tungsten film under fluorescent lighting.
- Heliopan cuts, grinds, polishes and coats their filters with the same techniques and equipment as used for the finest German camera lenses
- All Heliopan screw-in type and series size filters are mounted in precision black anodized brass rings to eliminate binding or cross threading and to ensure optimal alignment
- Filters still retain front threads for a lens cap, a lens hood or even stacking a second filter
- The portion of the Heliopan slim filters that are in front of the lens have been reduced in thickness by 37% over the former mount