Digital Photography Technology

Camera filters are a way to improve your photography. If you are not happy with your pictures and are serious about making them better, start looking at and understanding filters. They may not be the complete answer, but it could be a start.

Camera filters come in a variety of shapes and sizes, round, square, and rectangular and made of glass or plastic. Most of them are round and will thread into the front of most lenses. There a filters for black and white, color films, color digital, and infrared. Some of them are can be used with any type of film or digital. They can be stacked for special effects. All have a purpose, they either filter something out or allow something to come into the camera.

With the advent of digital photography and the digital processing software that is available, many of the effect that were done with filters on the can now be done with a computer. There still are some effects that can be done with a filter that can not be done on the computer. Even though the effects can be done on the computer, it is sometime easier to do them on the camera instead of spending all the time on the computer.

We will start by describing the basic and common filters, and then go in to the specialty filters.

The ultraviolet or uv filter is normally kept on all the time. It helps to reduce haze in out door shots, and protects the lens on the camera from accidental damage. A polarizing filter help to cut down glare on shiny surfaces. This helps to take a picture through a window and objects that are below the surface of the water. When taking a picture of the sky, it can enhance the blue color of the sky if color film is being used, and darkens the sky when using black and white film. The filter is a gray in color and is in a rotating holder. The effect of the filter can be seen by rotating the filter until the desired effect is seen in the view finder or the LCD monitor.

There are two types of polarizing files; circular and linear. The circular polarizer can be used with any camera and specifically one that has auto focus. A linear polarizer will confuse the automatic exposure and focusing of the camera. The linear polarizer can be used with any other type of camera, and is the least expensive of the two. The graduated neutral density, (ND), is another very useful filter that all photographers should understand. The filter comes in various degrees of density and is used to reduce the amount of light coming to the camera. There are times when there is an excessive amount of light for the picture that you are taking. The filter comes in various densities, starting at a .1 which is equal to 1/3 of a stop and up to 4.0, which is equal to 13 ½ stops. These filters also come in split versions, where light can be reduced in a portion of the picture. An example would be an extremely bright sky, with the lower portion of the picture relatively dark. A split ND would reduce the light from the sky, as to not over expose the picture.

The ND filter can be used with any type of film or digital format. It is a neutral grey, and has no effect on color.

The above are the three basic types of filter which everyone should have and use. The next groups of filters are used for color photography only. Correction is needed when using color print film, color slide, or digital color.

When taking pictures on a overcast day, a slight shade of blue will be visible on the picture. An 81A series filter will help reduce the blue and an 81B filter will take away more than the 81A. An 81C filter will take away the blue, but also give the picture a slightly warm color. An 81EF will be slightly warmer than the 81C.

The 82A filter is used to reduce the reds and yellows in the early morning and late afternoon sun. Print film is not as critical, as the corrections can be made when prints are being made. Color slides are more critical, because what you take is what you get. The correction has to be made when the pictures are taken.

When taking pictures with a digital camera, many of the better cameras have menus that can be changed for color correction in the camera. This solves the need for some of the above filters.

Black and white photography, which uses panchromatic film, records all colors in various shades of gray. Filters are used to change and make certain colors lighter or darker. The four common colors variations that are used are red, blue, green, and yellow. The problem arises when taking a picture of two colored subjects. They could both end up having the same shade of gray, which would make the picture looking rather drab without any contrast.

To solve the problem, a filter is used to pass one of the colors, which will make it lighter. Now there will be a difference between the two shades of gray, making the picture more attractive. The subject can also be made darker by using the correct filter.

This subject of filters with black and white film will be discussed in more detail on another page.