3x3" (75mm) 85N9 Color Conversion Wratten 2 Optical Gel Filter - Using tungsten film in daylight will produce a bluish cast in the photograph. The 85 series will produce natural colors when shooting with tungsten film outdoors. A #85 filter will decrease the color temperature from 5500K to 3400K and produce slightly cooler results than an 85B.
This filter combines an 85 conversion filter with a Neutral Density .6 (two stops) filter.
Most Kodak gelatin filters are available in 3 x 3" (75 x 75mm), 4 x 4" (100 x 100mm), 6 x 6" (150 x 150mm), and 14 x 18" (350 x 450mm).
Wratten 2 Improvements
Easier to handle
Color consistent today, and 6 months from now as well
Wratten 2 Optical Filters are less sensitive to humidity, less prone to static cling
Fingerprint removal is also easier
85 Series Color Conversion Chart
An 85 decreases the color temperature from 5500-3400 degrees Kelvin
An 85A decreases the color temperature from 5500-3100 degrees Kelvin
An 85B decreases the color temperature from 5500-3200 degrees Kelvin
An 85C decreases the color temperature from 5500-3800 degrees Kelvin
Neutral Density filters have four main uses
To enable slow shutter speeds to be used, especially with high speed films, to record movement in subjects such as waterfalls, clouds, or cars
To decrease depth of field by allowing wider apertures to be used, which helps separate subjects from their background
To decrease the effective ISO of high speed film (above ISO 400) and allow it to be used outdoors in bright situations
To allow cine and video cameras (which have fixed shutter speeds) to film subjects such as snow, sand or other bright scenes which could cause overexposure
Neutral Density factors
ND.3 (exposure adjustment = 1 stop, reduces ISO 1/2)
ND.6 (exposure adjustment = 2 stops, reduces ISO 1/4)
ND.9 (exposure adjustment = 3 stops, reduces ISO 1/8)
ND1.2 (exposure adjustment = 4 stops, reduces ISO 1/16)