Filters affect a light source and alter the appearance of the final image. What can filters do? They change the proportion of colors in the light hitting the film as well as changing the behavior of the light waves themselves.

Filters that change the colors content of light are colored and are referred to as CHROMATIC. The main functions of chromatic filters are to correct for color imbalance, or color correction, or to control color contrast. They offer very strong colors.

Filters that physically change light waves and have no color are classified as NON-CHROMATIC. They can be used to modify the light by decreasing its intensity, cut down on glare and reflections, change the sharpness or focus range, or remove part of the non-color spectrum that film is sensitive to, especially ultraviolet section. Some of these changes may be accompanied by an apparent change in the color of the final image, i.e. the secondary effect.

The third group which is the special-effect filters. They are designed to produce a wide variety of effects, utilizing both chromatic and nonchromatic mechanism.

Tungsten light sources have low levels of blue – tungsten-balanced films have large amounts of blue in their emulsions. When combined, the light sources produce the correct proportions of blue. This is why when you use tungsten film in daylight, which already has a significant amount of blue; you get a strong blue cast. If you add a conversion filter, it will block all colors except its own, it allows this color to pass. 80A filter enables you to use daylight balanced film, which has proportionally more of its emulsion sensitized to the red-yellow end of spectrum, under tungsten light with its high red-yellow content. The blue of the filter holds back much of the red-yellow, but allows virtually all the blue to pass through. The end result is a color-balanced picture. Putting a blue filter on your lens isn’t adding more blue than is already in the light. You are changing its proportion in relation to the other colors particularly red-yellow by blocking those wavelengths.

Color-compensating filters – compensate for the color shifts that occur during long exposures. They are also in different densities.

(Additive colors – red, green & blue) (Subtractive colors – yellow, magenta & cyan)

Employ conversion filters to shift Kelvin temperature for dramatic mood effects. Use 80A/B tungsten-conversion filter introduces a strong blue cast in the midtones and shadows, leaving the hightlights less affected. Gives the appearance of an increase in contrast, conveys a mysterious mood. E.g. shooting at the seashore when mist or fog is present. They also worked best on overcast days, silhouettes, increase cold appearance of snow scenes as well as cloudy days at sunrise/sunset.

Using the 85-series filters with human subjects for extreme mood shifts tends to be more appealing because the effect is a strong, reddish-yellow warming.

There are only 3 situations when film and light are theoretically color-balanced: when daylight film balanced for 5500K is used for shooting in sunlight with that same Kelvin rating, and when tungsten A and B films are used under standardized light sources of 3400K and 3200K respectively.

However, it is common to have variations in daylight because its Kelvin temperature changes throughout the day, as well as in tungsten sources because of the aging process of the lighting filaments. Even studio flash units can show some variations, but this is consistent for each model. You shouldn’t mix different brands of flash in critical color work. Smaller, on-camera flash units are notorious for their cooler color temperature.

81 series – colored yellowish-amber, decrease the Kelvin temperature in increments of several hundred degrees. The primary function is to use reach as perfect a Kelvin balanced between the light and the film as possible. The second function is to use them to add warmth to an already properly balanced scene. For example, decrease the Kelvin temperature of an outdoor, summertime portrait 200-degree with an 81A.

82-series – colored light blue, which increase the temperature over a similar range. They increase the Kelvin rating of a snow scene 300-degree with an 80B filter accentuates the mood of such shot.

They are used when you are shooting tungsten film outdoors or daylight film indoors. There is a massive shift in the blue or red-yellow portion of the spectrum. Tungsten’s heavy blue content imposes that color onto a daylight scene, and the excessive red-yellow content of daylight film adds that hue to a scene shot under typical indoors light.

The secondary effects are: they change the drab gray of an overcast day to a cool, mysterious, deep blue by using an 80-series filter with daylight film. When you are shooting a fireplace scene indoors under typical household lighting with tungsten film and an 85-series filter results in an extremely warm image.

How does this work? All chromatic filters remove part or all of certain wavelengths, thereby changing the proportions of color in the light reaching the film. This is because tungsten light sources have low levels of blue, tungsten-balanced films have large amounts of blue in their emulsions. When you combined them, the light sources produce the correct proportions of blue.

Using daylight film on an overcast day produces dull, grayish landscapes that appear flat. By using an 80B or 80A, it will introduce a strong blue cast in the midtones and shadows, leaving the highlights less affected. This gives the appearance of an increase in contrast, but it even strongly conveys a mysterious mood. This technique works best on overcast days. If you were to use it on a sunny day, it gives the impression that you are using the wrong Kelvin temperature.

You can also use 80A or 80B with silhouettes where there is enough illumination in the shadows to allow the blue to come through. These filters increase the cold appearance of snow scenes. They are appropriate on overcast or cloudy days and at sunrise & sunset. In addition, you can use them on a white person.

On the other hand, 85-series are used on human subjects for extreme mood shifts tends to be more appealing because the effect is a strong, reddish-yellowish warming. They are very appropriate for late-afternoon, sunset, and sunrise shots.

Moreover, you can use them at fireplace setting in which the flash is employed to fire the main light of the fire, which illuminates the subjects’ faces. The 85-series take out the blue of the flash and really warmed up the fire. You also add a diffuser or soft-focus filter to enhance the mood, giving it a dream-like, ethereal quality.

Fluorescent light, kind of non-standardized lights source. Unlike white light with its continuous spectrum, fluorescent tubes have a discontinuous spectrum of color that produce a different in proportions of colors present.

Please take note that you shouldn’t use the shutter speeds faster than 1/60 sec since fluorescent light comes from gas-filled tube that is electrically charged, producing a source prone to flickering. Any solution to different sources of light? Use 3 exposures on one frame:

It decreases the amount of light reaching the film without changing any other attribute of light.

Why do you need ND filters?

They are used to focus nearer to a subject without any loss of light transmission. They decrease the minimum focusing distance of a lens. However, the more magnification you used, the more sharpness that would drop off. Therefore, it is advisable to use only 1+ close up filter if you want to maintain good image quality. Alternatively, you are better off with a macro lens.

These filters work best with standard lenses or short tele-lenses of about 100mm and in low strengths of +1 on flat subjects. You must stop down from the maximum aperture by 2 or 3 stops, which is the customarily the sharpest aperture. For 3-D objects, use a high diopter power of +2 or more but you experience loss of sharpness, especially at the edges of your images.

The surface is so reflective that no significant diffusion of the rays occurs to scatter them in all directions. Instead, most of the light reaches the surface and then bounces off at the same angle. The light therefore remains concentrated and doesn’t dissipate – direct reflect – causes very little loss of light. To see a mirror reflection of a light source, you have to be within its angle of reflection.

Glare is a variant of a mirror reflection with one importance difference. The light becomes polarized as a result of the reflection and therefore isn’t as intense as the light source itself.

They penetrate the UV-abundant atmosphere. Haze refers to the combination of water droplets, dust, and increasingly pollution. This mixture lays on the horizon in a band of gradation that sometimes extends upward into the higher levels of the sky. When the light rays hit this assortment of particles, 2 visual effects are produced: a separation of some of the color wavelengths and a scattering of the rays.

In color photography, the effect of distant haze is a noticeable bluing. As for B & W photography, a general loss of contrast and a ‘graying-down’ of the distance tonal scale are noticed. The major causes of both effects are the scattering of the wavelengths, especially at the blue end, and the UV radiation’s impact on the film.

They introduce fog where none is present or increase its effect. Unlike the much smaller particles of haze, mist and fog are made up of larger droplets of water. The water causes 2 things to happen: light passes through the mist or fog, thereby allowing the red end of the spectrum to pass, scattering blue. Also, light hitting from the camera position reflects black and blue and passes the red through the result is a white, translucent cloud with a bluish cast.

A type of ND filters since it blocks light without producing any color shift. It darkens skies in B & W images and renders them much blues in color shot while maximum the saturation of all colors.

Light strikes a surface, it can react several ways – go through it, absorbed by the subject, reflect or bounce off the surface of the subject. When light does reflect – it does in 3 ways:

Angles between 30 and 35 degrees cause the most polarization. As these vertically vibrating rays come toward you, they are very bright and therefore obscure the diffused rays coming off the surface they are hitting. If this glare’s reflecting off shiny wood or glass picture frame, you won’t be able to see the diffused light of the grain or the picture behind the glass. What you will see is the shine of the vertically polarized, bright light.

Polarizers set to block only those vertically polarized, vibrating waves of glaring light, thereby letting the diffused light from the subject, which has waves undulating in all other directions through. You will be able to see the reflected, diffused light of the shiny wood and the picture in the glass frame without interference of the polarized glare.

The objective is to stop glare, not a particular wavelength of color. This explains why polarizers are able to make all colors appearing more saturated. These filters remove the glare from shiny leaves and from the surfaces of shiny objects. As a result the diffused light of the subject isn’t overexposed. This also reveals why these filters are capable of removing light reflections that typically appear on large glass areas. If you look at the sky through a polarizer at various angles to the sun, you will see the changes, from the very dramatic changes to none at all. This is because the area of greatest effect is set at a 90-degree angle to the sun.

They introduce color areas that often lack any color, such as overcast or cloudy scenes and areas of water in a foreground.