Photographic filters are an accessory to your camera and they come in many shapes and can be made from glass or other materials. For our purposes filters are made of glass and they are held within a slim metal ring. They attach to your camera by way of threading at the very end of your lens.
The basic photographic filter is intended to be mounted upon the barrel of your normal, zoom, wide angle or macro lens in a way that light entering the camera must first pass through the filter. Most photographic lenses will already have the treading needed to do the job. The filter’s purpose is to modify light in some way as it enters the camera lens on its way to registering an image inside the camera. There are many reasons you might want to modify the light entering your camera. They relate to improving the quality of the image or to adding special effects.
State of the art image processing software allows you to modify any image to get improved results. However, the best image process begins with an original image that meets high standards. A filter will help you get the results you want from many situations.
Photographic Filter Facts
Some Negative Factors – Learn how to use filters properly or else they could ruin your pictures. Also, filters add to the cost of photography, complicate the process of taking a picture, and make your camera bag heavier and more cluttered. Also note that some types of filters actually reduce the amount of light that enters your camera so that more light is required or more compensation is needed in the form of increased aperture and/or slower shutter speed to take pictures.
Why Use Filters? – Filters will improve the quality of your photos. Some filters can reduce haze. Some can remove surface glare and make the sky as blue as it looks to your eyes. Some filters intensify the colors in your photos. Others can bring sparkle to parts of your photos or add other special effects. There are even some that can improve your photos while protecting your expensive camera lens.
Educate yourself on the subject of filters so that you can get the most out of your photographic interest without wasting money on items you don’t really need. Read your camera’s manual to see if it can take filters. If you lost the manual, look for threading in the metal around the front end of the lens surface. You may also find a printed number there, usually followed by “mm” (millimeters), that tells you the right filter size. Don’t go out and buy a filter until you know what size your lens requires.
Not just any filter will fit any lens. For example, the normal lens for my Minolta is also a macro lens. It takes 55mm filters. It would not be unusual for the telephoto lens and the wide angle lens for the same camera to require different filter sizes. This will most often be the case when the lenses are not purchased from the original manufacturer or when you have purchased additional cameras over the years. Different brands of lenses and cameras will take various sizes of filters. One answer to this issue is called a “converter”. In the best example converters may allow you to use one set of filters on all your lenses.
Types of Filters
Clear – Clear filters lack coatings or any design that would affect light transmission. They are only intended for protection of the front element of the camera lens.
Skylight, Haze & UV Filters – These filters do not require exposure adjustment. They partially block invisible ultraviolet light that is a natural part of sunlight. Although this light is invisible to us it’s effect can be seen in your pictures as an excessive blue cast in shaded elements of the scene and poor contrast. When there is haze it can negatively impact your outdoor shot. The effect of haze is most noticeable with telephoto lenses. These filters can also reduce atmospheric haze in your pictures.
From my experience, the skylight filter is most valuable when kept on the lens at all times. Many people prefer to use a UV filter this way. The skylight will serve to protect the top lens element from normal wear and reduce the possibility of impact cracks. It was a skylight filter that took the hit and cracked when I dropped my camera bag on a rock. That $12 filter saved my 200mm telephoto. You can’t count on this protection in all cases but when it happens you feel pretty smart for having the filter in place.
Neutral Density Filter – This filter is used to intentionally reduce the amount of light entering your lens. The effect is helpful when you want to limit depth-of-focus in a bright light situation.
These Filters are solid gray and are used to reduce the amount of light passing through the lens. They result is an overall reduction of exposure which requires longer exposure time. They are available in a range of densities. They can be used to manipulate depth-of-field or to blur moving objects. Variable neutral density filters provide a range of exposure options in one filter. The variance is produced through two opposing polarizing filters that can for rotated while you select the desired result.
Fluorescent Light Filters – will help improve the greenish cast from fluorescent bulbs. Results are not 100% because of the various types of florescent bulb. However, you should expect to achieve more pleasing skin tones and more natural color rendition.
Color Filters – Color filters are most commonly used to enhance B & W photos. For example a red or orange filter can make for dramatic black and white photos with exposure balance between sky and land. If you use a color filter with color film you’ll get an overall tint that can be considered a special effect.
Polarizing Filter – This filter reduces glare. That may not sound like much at first, however, the polarizing filter is very powerful and rewarding to use.
What about glare? – For our purposes I will define glare as light reflected from the surface of a nonmetallic object. Such light is reflected along a single plane. The polarizing filter can be rotated in its mounting to an angle where glare is blocked. This effect seems much more significant if you have to ask yourself why the landscape pictures you took on that clear October day lack the sharpness and depth of color that you saw when you decided to take the pictures. The glare effects occur largely from factors over which you have limited or no control, such as the angle to the sun and the composition of the very top surface of the object you are photographing.
Glare negatively affects the quality of many photographs taken in natural light. Pictures taken by incandescent light indoors can also be affected. Surfaces that commonly produce glare include bodies of water, window panes, and treated wood surfaces. Another common source of glare is air. Actually it’s the dust particles and droplets of water that are suspended in the atmosphere all the time.
The glare-blocking effect of a polarizing filter reduces unwanted glare in a photographic image while intensifying colors in your photograph. This filter is designed to be rotated according to the current light conditions. You can check through the viewfinder of a Single Lens Reflex camera to determine the exact effect of the filter and to experiment in real time as you desire.
Rectangular Filters – These are compatible with your lens through the use of a dedicated filter holder. They are useful for graduated filters because you can adjust the areas of transition more freely than with circular filters.
Filter Coatings – There is a range of coatings available for use with a lens. One or more coatings can be applied to the lens to increase light transmission as well as to prevent reflections and glare. Other types of coating are available to reduce the effect upon the lens from scratching, water, fingerprints, smudging or static. Coatings make it easier and safer to clean the surface of the lens.
Step-Up and Step-Down Rings – These gadgets save you money by allowing lenses of different threading sizes to share filters. Be careful that step-down rings may cause vignetting.
Some benefits of a polarizing filter:
a. Blue skies that become a much deeper and more intense blue. This difference is easily to see.
b. Increased control over photographic situations such as more latitude in choosing your shooting angle and better matching of the sky to the ground features.
c. Improved detail, depth and contrast in wood grains and in the color patterns of wood in items such as a rifle stock, a desk or a wooden carving.
d. Picture elements such as the leaves of a tree and other foliage will reveal their true colors and patterns to a polarizing filter.
e. Shoot a lake scene and actually see a few feet into the water if it’s clear enough.
f. Haze that is reduced more than with a UV or Skylight Filter.
Polarizing filters I have used consist of a rotating collar that can be smoothly rotated to the angle that is required to block unwanted glare. A well-made filter will also maintain its setting while the picture is taken and will have a small handle that makes the process easier.
On an overcast day the polarizing filter will have no effect. However, when the sky is blue or partly cloudy you can get a dramatic difference. It is important to remember that time of day (another way to say the angle of the sun) makes a big difference to how much a polarizing filter can improve your photos.
Photographing in sunlight from the street through a jewelry store window toward displays inside is a scenario that will demonstrate the problems glare presents when you try to shoot through glass. Frequently in this situation you would barely be able to see the actual jewelry due to the glare in the window glass from the street behind you. The polarizing filter will frequently be able to remove all the glare and reveal the detail your subject.
Notable Considerations with Filters
The first thing you may say when you try any of these filters with your pictures is something like, “So . . . that’s how the professionals do it!” However, not every effect will show in every picture and not all cameras will work well with filters:
a. If the sky is an important element of your photos, learn to shoot the sky when the sun is at the best angle to produce the polarizing effect. If the sun’s angle is too shallow the polarizing effect will be minimal to unnoticeable. Your adjustment ring may not always be able to compensate fully. Again, when shooting outdoors on sunny days you’ll get your best results before 10AM or after 3PM.
b. A Single Lens Reflex camera is best suited for efficient use of filters.
c. Exposure will have to be increased to compensate for the light loss through some filters such as a polarizing filter. Therefore, you will be less likely to use these filters when stopping high-speed action or in low light conditions.
d. Using a polarizing filter can actually over-saturate a blue sky to the point that it looks very unnatural.
e. Filters that intentionally distort light, such as a starburst filter, can be great fun and will give interesting photos. Some people like to take all their original shots with the best possible quality and add such effects through photo editing.