The Cokin Z-Pro 028 81C Color Conversion Resin Filter controls the bluish coloration that affects daylight film. An 81C will render skin tones nearly normal as well as eliminate the stronger bluishness of open shade on very clear days. The 81C is slightly stronger than an 81B and is also used for general landscape photography on cloudy days as well as to add additional warmth in portrait photography.
It's Autumn. The clouds are low hanging and the sky is "patchy blue". You've gone for a ride upstate to the mountains and the light in open shade is bluish. A photo taken of your girlfriend with daylight balanced film leaning against the side of a barn will yield bluish tones that she might not find particularly flattering. An 81C filter will replace even more yellow than an 81B and place her skin tones on a more "warmish" level.
An 81C can also be used with electronic flash to reduce the amount of "blue" generated by the flash. The 81 series (81A, B, C, D and EF) allows you to choose how much warmth you wish to replace in the image.
The Z-PRO Series is recommended for focal lengths of 20mm onwards (in the 35mm format). This filter is made of CR39 Resin which is a reputable lightweight and unbreakable optical material also used for ophthalmic glasses.
Note! Whereas the 81 Series of filters creates a feeling of warmth, the 82 Series creates a feeling of coolness
| Type | Z-PRO Color Conversion |
| Size | 100 x 150mm (4 x 6"), 1.5mm thick |
| Grade | 81C |
| Filter Factor | 1.2 (+1/4 stop) |
| Multi-Coated | No |
| Rotating | No |
| Effect | The 81 series adds warmth to the image |
| Application | Good for general scenics when the photographer wishes to remove the bluish cast from open shade or just add warmth to the photograph, with an 81EF having the greatest effect |
| Color Temperature | Decreases color temperature from 3600 - 3200 Kelvin |
| Construction | CR39 Resin |
| Front Filter Thread Size | Not Applicable |
| Front Lens Cap Size | Not Applicable |