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Wednesday, September 22, 2010

Camera Filters

One question that i get asked all of the time is about camera filters. Filters come basically in three categories.

* Light Modification
* Special Effects
* Color Correction

This blog is about ND filters and how to use one on your video camera to get a shorter Depth of Field, or shallower in focus, thus getting more of a film look without using a DOF adapter. 

Neutral Density filters are used for light modification and are the filters that get used the most. On many Prosumer camcorder ND filters are included.

The thing about a Neutral Density filter is that it reduces the amount of light without changing the color or quality of the light.
On film and video cameras ND filters have three main uses.
* To decrease DOF by allowing wider apertures to be used, which helps separate subjects form the background.
* To decrease the effective ISO of high speed films above 400 and allow it to be used outdoors in bright situations
* To allow film and video cameras with fixed sutter speeds to film subjects that are bright like snow or sand without overexposure.

ND filter come in four main factors. Or thicknesses.
* An ND.3 often referred to as just an N3 or ND3 cuts 1 stop of light, or reduces the ISO by half.
* An ND.6 often referred to as just an N6 or ND6 cuts 2 stops of light, or reduces the ISO by 1/4 (this is usually the first ND setting in a prosumer camera referred to as a 1/4 ND.)
*an ND.9 often refered to as just an N9 or ND9 cuts 3 stops, or reduces the ISO by 1/8.
*An ND1.2 often referred to as an N1.2 or ND1.2 cuts 4 stops, or reduces the ISO by 1/16 (this is usually the second ND setting in a prosumer camera referred to as a 1/16 ND.)

One thing that video cameras tend to have is a very deep DOF. By zooming as much as possible and adding the appropriate combination of filters you can open the iris as much as possible and this will shorten the DOF thus providing a out of focus background. When you zoom in you will need to physically back your camera up from your subject until the size of your subject is about the same in frame as when you were on a wider angle lens setting.

Go try it. Experiment and have some fun getting that out of focus look that is so desired.

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