Camera Lens Filter

Camera lens filters still have many uses in digital photography, and should be an important part of any photographer's camera bag. These can include polarizing filters to reduce glare and improve saturation, or simple UV/haze filters to provide extra protection for the front of your lens. This article aims to familiarize one with these and other filter options that cannot be reproduced using digital editing techniques. Common problems/disadvantages and filter sizes are discussed towards the end.

The most commonly used filters for digital photography include polarizing (linear/circular), UV/haze, neutral density, graduated neutral density and warming/cooling or color filters. Example uses for each are listed below:

Filter Type	Primary Use	Common Subject Matter
Linear & Circular Polarizers	Reduce Glare Improve Saturation	Sky / Water / Foliage in Landscape Photography
Neutral Density (ND)	Extend Exposure Time	Waterfalls, Rivers under bright light
Graduated Neutral Density (GND)	Control Strong Light Gradients Reduce Vignetting	Dramatically Lit Landscapes
UV / Haze	Improve Clarity with Film Provide Lens Protection	Any
Warming / Cooling	Change White Balance	Landscapes, Underwater, Special Lighting

Taking Photos in fog, mist or haze

Photography in fog, mist or haze can give a wonderfully moody and atmospheric feel to your subjects. However, it's also very easy to end up with photos that look washed-out and flat. This techniques article uses examples to illustrate how to make the most out of photos in these unique shooting environments.

OVERVIEW

Fog usually forms in the mid to late evening, and often lasts until early the next morning. It is also much more likely to form near the surface of water that is slightly warmer than the surrounding air. In this techniques article, we'll primarily talk about fog, but the photographic concepts apply similarly to mist or haze.

Photographing in the fog is very different from the more familiar photography in clear weather. Scenes are no longer necessarily clear and defined, and they are often deprived of contrast and color saturation:

In essence, fog is a natural soft box: it scatters light sources so that their light originates from a much broader area. Compared to a street lamp or light from the sun on a clear day, this dramatically reduces contrast:

Scenes in the fog are also much more dimly lit -- often requiring longer exposure times than would otherwise be necessary. In addition, fog makes the air much more reflective to light, which often tricks your camera light meter into thinking that it needs to decrease the exposure. Just as with photographs in the snow, fog therefore usually requires dialing in some positive exposure compensation.

In exchange for all of these potential disadvantages, fog can be a powerful and valuable tool for emphasizing the depth, lighting, and shape of your subjects. As you will see later, these traits can even make scenes feel mysterious and uniquely moody -- an often elusive, but well sought after prize for photographers. The trick is knowing how to make use of these unique assets -- without also having them detract from your subjected.

Importance of Moonlight

Just as how daylight photographers pay attention to the position and angle of the sun, night photographers should also pay careful attention to the moon. A low-laying moon can create long shadows on cross-lit objects, whereas an overhead moon creates harsher, downward shadows.

An additional variable is that the moon can have varying degrees of intensity, depending where it is during its 29.5 day cycle of waxing and waning. A full moon can be a savior for reducing the required exposure time and allowing for extended depth of field, while a moonless night greatly increases star visibility. Furthermore, the intensity of the moon can be chosen at a time which provides the ideal balance between artificial light (streetlamps) and moonlight. Gauging exposure times during a full moon can be tricky; use f/2.0 and 30 seconds at ISO100 as a starting point (if subject is diffuse and directly lit), then adjust towards scenarios 1-4 accordingly if OK. Another factor rarely noticed during daylight is movement of the light source (sun or moon). The long exposure time required for moonlight photography often means that the moon may have moved significantly over the course of the exposure. Moon movement softens harsh shadows, however too much movement can create seemingly flat light.

Photograph Under a Full Moon

Note how the 1 minute exposure above clearly shows high contrast and shadows from even the smaller branches, whereas the 4 minute exposure is at lower contrast and only shows the larger branches. The choice of exposure time can also vary by much more than a factor of four-- greatly exaggerating the above effect.

Crop of Tree Shadows on Path:

Choose Exposure Time:

Photograph Under a Full Moon 1 minute 4 minutes  

Shots which include the moon in the frame are also susceptible to moon movement. A rule of thumb is that the moon appears to move its own diameter roughly every 2 minutes. As a result, it can quickly appear elongated if this exposure time is approached.