Using coloured filters with black & white film

Experienced black & white photographers often use a filter to adjust the tonal range of a photograph. This article will help you understand what happens and guide you to the filters to use for different subjects.

When we take a photograph in black and white all the colour is replaced by a series of greys from black to white with mid tones at around 18% grey. Your viewer has to imagine colour and you sometimes have to work harder as a photographer to get a picture that looks as impressive as a colour version. One of the problems is that unless you can identify with the original colour you may not be able to distinguish one hue from another. For example, a crimson red may look very similar to a leaf green when viewed through black & white. To help you view an image as it will appear you can buy a monoview filter which shows a rough view of the world in black & white. With a digital camera used in black & white mode you could shoot a photograph and then view the tones on the LCD preview.

By placing a filter over the lens you can dramatically change the tone so a colour becomes darker or lighter grey. You may have seen a black & white landscape photograph with the dark blue sky turning almost black. The chances are this will have been taken with a red filter over the lens.

Filters allow certain wavelengths of light through and block others from reaching the film. The filter will let through it's own colour so the grey tone of subjects with the same colour as the filter will be lighter and the tones of subjects with contrasting colours will become darker.

The following filters are commonly used in black & white photography: Yellow, Orange, Red, Blue and Green, and the visual below shows what happens to the tones when the filters are used.

Original colour photograph for reference shot on a blue/grey background.

Photograph taken in black & white with no filters used. Notice tones such as orange and light pink become almost identical so do blue and red.

Adding a yellow filter introduces a subtle change to to yellows, oranges and red which become slightly lighter.

The orange filter lightens oranges and reds and darkens the blue and green pencils.

It's the red filter that has a serious effect on tones. Notice the pink and orange are now almost white while the deep red displays similar values to the original orange. While the blue and green have become very dark.

The green filter can be seen affecting the blue and green pencil which become much lighter while the orange and red ones go darker

The blue filter has a similar effect on colours, making reds and oranges become a touch darker and blues and greens slightly lighter.

Which one should I buy?
Changes using the yellow filter are subtle so it's used by many photographers as a lens protector and most benefit is seen in landscape photography where the effect on blue is just enough to make a light sky a shade darker than the print's border.

The orange lightens reds so it's favoured by portrait photographers who use it to reduce freckles and skin blemishes. Architectural photographers also find it's affect on bricks useful. This out of all the filters is arguably the most practical and should be a definite first on your shopping list.

Red is for the creative photographer who likes contrasty results, as tones are dramatically affected. It's also used by infrared photographers as an alternative to the true infrared filter and very popular with landscape shooters.

Green is less popular in the black & white photographer's kit, but would be appreciated by landscape photographers as it affects greens and can help differentiate between foliage making the whole scene come to life. The downside is it lightens the blue in a sky so the overall contrast may suffer.

Blue is little used for black & white work and would mostly be considered as a contrast reducer which you can often do satisfactorily using a different paper grade.