What is a Fog Filter?

Many people will find fog in their video image from a number of different sources, yet it is almost always an obstacle. Fog appearing in your footage, whether it is there from an actual weather condition or a combination of environmental factors, robs the image of clarity and contrast. On the other hand, this is actually a digital video effect that you may want to employ for different reasons. To do this effectively you may want to use a fog filter on your digital video camera lens.

Fog filters, unlike other types of digital video filters, will do exactly what it says. It will give a glowing haze around the objects making them have an almost dreamlike appeal at times. What it does inherently to the digital video image is lower the contrast in that image. The degree of fog filter that you use is dependent both on the situation you have and the amount that you want.

If the scene itself, with the objects and the lighting situation, is low in contrast already you will want to use a lower grade of fog filter. If you use a higher level of fog filter then you may make it hard to see at all. On the same note if there is a scene with fast light fall off and a large amount of color contrast you are going to need a stronger degree of fog filter if you intend on seeing that filter applied.

Fog filters are good at adding the strange glow, but not really that good at actually recreating the exact look of fog. The reason for this is that fog itself is an object in the environment and has a very specific relationship to that environment in how it alters its appearance. For example, if you get close an object becomes more visible through the fog. The fog filter, on the other hand, will make all objects equally lacking in visibility.

Try to save the fog filter for appropriate uses. Audiences generally have a certain expectation when a fog filter is used. These are conventionally used for flashbacks, dream sequences, or to remind people of a different period of time. Only use it if you have a clear reason to do so because it actually limits your ability to craft an image. You do not have to rely entirely on the audiences expectations, but it is important to at least keep them in mind.