MASTER CUSTOM FILTER DENSITIES

Learn to get more from your filters by creating un-stepped strength effects, for a bespoke shooting approach to any scene

Experiment with this shooting approach

There is a huge variety of photographic filters available, each providing characteristic effects for virtually any situation. However, despite this choice, the most popular types are available in stepped densities which, while great for common exposure conditions, may not provide the exact level of filtration required by the photographer. For example, neutral density (ND) filters most often come in one, two, three and four-stop strengths, providing 50%, 25%, 12.5% and 6.25% light transmittance respectively.

On occasion you may find that one filter is not strong enough, but the next density is too much for your scene. Perhaps a 0.9ND doesn’t give a long enough exposure, but a ten-stop model is undesirable. When this happens, hand-holding an extra filter in front of the lens for only part of the total exposure can help achieve the required filtration, for an intermediate exposure duration or a custom darkening of the sky, using an ND gradient filter. With the latter, hand-holding can give more control over the softness of the gradient, if a soft grad is insufficient but a hard grad too obvious. When holding any filter, it is vital to keep it perfectly aligned with the lens to prevent extraneous light effects. Experiment and take full control of your exposures.

ALLIMAGES©PETERFENECH Inset OVER-FILTRATION A 0.6ND grad filter provided insufficient darkening to hold sky detail in this long exposure, but a 0.9 strength produced unnatural colours

BEFORE

1CALCULATE REQUIRED DENSITY Start by working out the difference in exposure between the sky and foreground. In aperture priority mode, take a meter reading from both zones, noting the EV variance in suggested shutter speed.

2COMPOSE YOUR SCENE Using a tripod, arrange your frame as required, positioning the horizon to control the ratio of sky and foreground. Switch to manual mode once the ideal exposure has been determined.

3ACHIEVE CUSTOM GRADIENTS For a feathered density transition, hold an ND grad with the gradient at the horizon. During the exposure, move the filter up and down, so the transition is softened around the horizon line.