Returning to black-and-white photography, I want to look at the role of filters. In At the Edge: Shooting High-Contrast Black and White, I argued that setting the camera to monochrome can help you learn to see shadows, edges and textures before taking the photograph. The same thinking applies to filters.
Coloured filters are not essential in digital photography, but they can still influence the way tones are rendered. Some effects can be recreated in post-processing, while others, such as reducing reflections with a polarising filter or extending exposure with an ND filter, are much harder or impossible to reproduce convincingly afterwards.
UV, polarising and neutral-density filters
A UV filter was once used to reduce the effect of ultraviolet light on film. With modern digital cameras, that role is generally less important. Some photographers use a clear or UV filter to protect the front element of a lens, while others prefer a lens hood and careful handling. A protective filter can introduce reflections or flare, so it is a choice rather than an absolute requirement.
Polarising filters can reduce reflections from non-metallic surfaces such as water and glass. They can also deepen blue skies and help reduce haze in some conditions. Their effect depends on the angle between the camera and the light source, and they reduce the amount of light reaching the sensor.
Neutral-density (ND) filters reduce the amount of light entering the lens without deliberately changing colour. They are useful when you want a slower shutter speed in bright conditions, or a wider aperture than the available light would otherwise allow. For a good introduction, see Peter Hill’s Ultimate Guide to Neutral Density Filters, and explore the Lee Filters range.
Coloured filters: yellow, red, blue, orange and green
For black-and-white photography, coloured filters change how different colours translate into shades of grey. The explanation at Photography Mad remains a useful introduction. The effect depends on the colours in the scene and the filter’s strength.
- Red: A red filter can create dramatic contrast, particularly by darkening blue skies and making clouds stand out. It can also significantly change skin tones and may require additional exposure.
- Orange: An orange filter gives a less pronounced version of the red-filter effect. It can darken blue skies and increase separation between clouds and the background.
- Yellow: Often the classic starting point for black-and-white film photography. It gives a moderate increase in contrast and can make clouds stand out against a blue sky without producing an overly dramatic effect.
- Green: A green filter lightens green foliage, which can help separate leaves and grass from darker surroundings. It can also affect how skin tones are rendered.
- Blue: A blue filter can lighten blue areas and darken some warmer colours, producing a softer or hazier-looking result in certain scenes. It is less commonly used, but can be interesting when you want a different tonal balance.
Filters are not magic, and there is no single choice that works for every photograph. The important thing is to understand how a filter changes the relationship between colours and tones, then use that effect deliberately.
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