How color filters work
A black and white image records brightness, not hue. A colored filter changes how bright different colors become. The basic idea is that a filter lightens colors similar to its own and darkens colors opposite to it. A red filter, for example, makes red objects appear lighter and blue objects, such as sky, appear darker.
Common filters
- Yellow. A mild effect. It deepens blue skies slightly and makes clouds stand out a little. Many photographers treat it as a general-purpose choice.
- Orange. A stronger effect than yellow. Skies darken more, and skin may look smoother or lighter, depending on the subject.
- Red. A dramatic effect. Skies can become very dark, and clouds stand out strongly. Landscapes may look high-contrast, and sometimes surreal.
- Green. It lightens foliage and can darken red tones. It is often used for plants and some portrait situations.
- Blue. It does the opposite of the warm filters, lightening skies and darkening warm tones. It is rarely used, though it can add atmosphere to haze or fog.
Filter factor and exposure
Colored filters block some light, so the exposure may need to be increased. This is expressed as a filter factor or in stops. Typical rough values are about 1 stop for yellow, about 2 stops for orange or green, and about 3 stops for red, but these vary by brand, film and light, so check the manufacturer’s guidance.
If your camera meters through the lens, the meter may account for part of the loss, but not always accurately, because meters respond to colors in their own way. Test and bracket if needed. The longer exposures may call for a steady camera, so see why a tripod matters.
Which filter for which subject
- Landscapes with sky: yellow for subtle, orange or red for stronger drama.
- Portraits: lighter filters are generally safer. Red can lighten skin and hide blemishes but may make lips look pale.
- Foliage and flowers: green can separate leaves from darker backgrounds, while red may darken leaves.
- Architecture and cityscapes: orange or red can add contrast between sky and buildings.
Drawbacks
- Less light reaches the film, so you may need a slower shutter speed or wider aperture.
- Strong filters can produce unnatural-looking skies if overused.
- Colors with similar brightness can become hard to separate.
- Filters add cost and one more thing to carry, and cheap glass can reduce sharpness.
Using filters on digital cameras
On a digital camera shooting in color, a colored glass filter changes the color channels you record, which often gives a strong color cast that needs adjusting later. A common alternative is to shoot RAW and convert to black and white in software, where you can adjust color sliders that act like virtual filters, as explained in what luminance is. Some cameras also offer monochrome filter effects in their picture styles. Physical filters still make sense on film, or if you like to see the effect in camera.
Tips
- Start with yellow or orange before trying red.
- Shoot a few exposures of the same scene with different filters to compare.
- Keep filters clean to avoid flare and smudges.
- Pick the filter size for your largest lens, or use step-up rings.
FAQ
What is the best color filter for black and white photography?
There is no single best one. Yellow is a common starting point, orange and red give stronger sky contrast, and green suits foliage.
Why would you use a red filter with black and white photography?
To darken blue skies and increase contrast between clouds and sky.
What is a black and white photo filter called?
Photographers usually say “contrast filter” or “color filter” for the glass type. In software it may be called a monochrome or black and white filter.
How do I add a black and white filter to a photo?
In a photo editor, convert the image to black and white and adjust the color channel sliders, or apply a monochrome preset.