I recently an old Canon O1 orange filter. According to the pamphlet on the filter, it says it works on monochrome film with a filter factor of 3x.
What effect would this filter give me on color film?
Thanks in advance!
Since black and white film records the overal intensity of light that reaches the film, colors that pass through the filter (orange) will appear brighter than colors that are blocked (blue and green), when used with black and white film.
With color film, color-tinted filters will tint the scene with the color of the filter, unless further corrections are made. Colors that are blocked by the filter will still appear darker. This applies to color-correction filters as well, where the tint of the filter counteracts a tint in the lighting.
A red filter will make a scene appear red. A green filter will make the scene appear green. A blue filter will make the scene appear green.
An orange filter will make the scene appear orange.
With few exceptions, a filter passes the color it is named and checks its complements (opposites). We mounted a yellow filter on a camera loaded with black & white film to darken blue sky. We did this because often white fluffy clouds, usually back-lit, reproduced about the same shade of gray as did the blue sunlit sky. If we wanted a more dramatic effect we mounted an orange or red filter. These darkened the blue sky even more without too much darkening of the clouds. The effect is more contrast clouds to sky.
An orange filter in conjunction with black & white panchromatic film, darkens cool colors and lightens warm colors.
If you mount a strong colored filter in conjunction with color film, you get a strong overall unnatural color cast. In this case, the orange filter will simulate some of the colors you see when the sun is low in the sky such as sunset and sunsets. Experimentation with filters is your best teacher.
A filter factor of 3X means that when daylight balanced light (full spectrum light centered on around 5500K) is passed through the filter, the total amount of light will be reduced by a factor of three (3), and one-third (one-third) of the original light will pass through the filter. One-third (1/3) the light is equivalent to one and two-thirds (1 2/3) stops. But if the filter is a color filter, all wavelengths/colors of light will not be reduced by the same amount. If the filter is a neutral density filter, the brightness of all colors/wavelengths of light should be reduced by the same amount.
For an orange filter, orange light will be reduced by less than other colors of light. The further a color is from orange around the color wheel, the more light that color will be reduced.
Color filters are often used in monochrome (B&W) photography to enhance or reduce contrast between things that are different colors in the scene being photographed.
Since the filter is orange, orange light passing through the filter would be reduced by a lesser amount than other colors of light. Blue, which is directly across the color wheel from orange, will be reduced by the most amount.
If there are orange and blue items in the scene that are the same brightness, without a filter they would both appear to be the same shade of gray in a monochrome (B&W) image of the scene.
By using an orange filter and increasing exposure to compensate for the filter factor, the orange object will appear to be lighter gray than before and the blue object will appear to be darker gray than before. If we used a blue filter, the opposite would happen. Our blue object would show up as lighter gray than the orange object.
With digital photography, the possibilities are much greater when saving raw image data. Different color filters can be applied during conversion from raw data to an image that will affect differently colored objects in the scene differently in terms of their tonal value (how dark or how bright a shade of gray they are).