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Using filters for punchy mono

Techniques

24 October 2007 09:35

When using black & white film it’s possible to use coloured filters to change the way that colour tones are recorded. With a digital camera, much of this tonal adjustment can be done on the computer, when you convert your digital image file from colour to black & white. However, certain filters can still be useful when using a DSLR.

A key technique for successful digital black & white is making sure the sky contains a full range of tones. However, it’s almost impossible to retain detail in the sky while correctly exposing the foreground unless you use a filter: when converted into black & white you’ll simply end up with a flat-looking, bland sky. So, rather than use the traditional red, yellow and green filters as you might when using film in the camera, there are two types of filters that are particularly useful for digital black & white – ND grads and polarisers.

Whether you’re shooting in colour or black & white, an ND grad filter allows you to darken the sky while leaving the foreground unaffected. This will help you to get more contrast in the sky and create a punchier image when you reach the conversion stage.

ND grads come in a range of strengths, most commonly giving a 1, 2 or 3-stop (also known as 0.3, 0.6 and 0.9 ND respectively) difference between the clearest and darkest part of the filter. For shots of blue skies you’ll find a 1 or 2-stop filter sufficient to retain detail, while shooting towards the sun you’ll need at least a 3-stop grad to retain detail in the brightest areas of the sky. For this shot, we used a 0.6 ND grad to darken the sky by 2 stops.

Polarisers can also reduce the amount of light reaching the sensor and are often used to darken blue skies and increase contrast between sky and clouds. Simply rotate the filter for maximum effect. 

For even greater impact you can also combine the effect of a polariser and ND grad filters. This can produce dramatic dark skies and help to add to the mood of your black & white landscape shots.