Type of filter

Filters have many uses, and we can divide them into the following categories according to different classification standards: 1) filters: they can adjust various colors in the spectrum.

2) Polarizer: Eliminate the shining reflection of light on the surface of the object.

3) Soft lens: Soften light.

4) Special effect mirror: starlight, multi-shadow, medium gray, ultraviolet ray, infrared ray, etc. 1) color film filter: high transparency, many colors, low cost, but fragile and easy to fade.

2) Glass sandwich filter: high transparency and many pigment grades, but the increase of thickness changes the focus and affects the clarity.

3) Colored glass filter: high transparency, thin texture, will not change the focus of the lens, and is resistant to damp heat. But the pigment grade is slightly worse.

4) Liquid color filter: the colored liquid is injected into a transparent container, the color is changed at will, and it is placed in front of the lens, which is mostly used for scientific photography. 1) weak color filters: such as No.0 yellowish color filter and No.0 yellowish color filter.

2) Neutral filters: such as No.2 and No.3 yellow filters and No.65438 +0 orange filters, yellow-green filters and light green filters. It is essential to shoot scenery, flowers, bonsai and still life.

3) Strong color filters: such as No.2 and No.3 orange, No.4 yellow, deep red and No.2 red color filters. Taking landscape photos can eliminate the mist in the air perspective and make the field of vision particularly clear. 1) UV filter (UV mirror): It has little effect on image clarity, so mountain photography is necessary, and color photography can eliminate the influence of blue and purple light.

2) Polarizing filter: the upper part is colored and the lower part is colorless, which is used to adjust the contrast between the sky and the scene brightness. It is best to use it to take photos of backlit scenery.

3) Infrared color filter: absorbs all visible light in the spectrum and only lets invisible infrared light pass through, which is used for infrared photography.

4) Fog mirror: used in landscape photography to increase the sense of space depth and air perspective and enhance the fog effect. Backlight and side light have good high beam effect, while front light has little effect.

5) Medium gray filter: It can absorb various wavelengths of light, reduce the brightness of the scene without affecting the color contrast, and is used when shooting in seashore, desert and snow with extremely bright light.

6) Change the film filter: daylight film is shot under the light, and yellow film such as Leiden 80 is added; The light film was shot in the sun, and the Leiden 85 filter was added. Let's talk about different types of filters used in color film photography. Although we don't always use color film in photography, color is undoubtedly the most used.

To our eyes, light is light. However, as we learned in film class, color movies are very sensitive to the color of light. For example, human eyes, the light on cloudy or foggy days is exactly the same as that on sunny days, and there is no difference. But for color film, these two kinds of light are different, different. Light passing through clouds or fog is bluer than direct sunlight. Color film can see this blue color and record it.

For color film, the light in an open shadow (for example, shooting an object in the shadow of a big tree in clear weather) is also blue. For example, when shooting the scenery of skiers at the top of the mountain, the light at the height is also blue. In all these cases, the light is blue, and our color film will also record this blue.

We don't want to shoot blue faces, but we want to shoot bright faces; I don't want to shoot blue pine trees, but I want to shoot lush pine trees. Therefore, we must take measures to remove the unnecessary blue light projected on the film. This problem can be solved by placing a filter in the light path where the light shines on the film.

How to make the light slightly blue? You can remove the blue filter a little. The filter numbered 1A is a traditional skylight filter with good effect, which is called skylight for short. The celestial mirror looks colorless, but it actually has a faint magenta color. From the perspective of color theory, magenta belongs to a color that can weaken blue. We know that the effect of 1A filter is the same as that of CC025M color compensation filter. The color compensation filter will be described in detail later.

What if the light is dark blue? Just use the crimson filter. We recommend that you use the 8 1A filter. If more intensity correction is needed, an 85C filter can be used. Then, why not use the deeper magenta filter and use the 85C model? This is because in some cases, the overall tone of the image color will become magenta, which is obviously not what we want. The purpose of using filters is to make the image closer to the natural landscape we see with our own eyes.

In actual shooting, how to determine whether the selected filter has enough color depth? In fact, we can't be sure until we get the finished slides or photos. But generally speaking, the filter numbered 1A is suitable for cloudy or foggy days, but the color depth is not enough for high altitude or outdoor shadow shooting.

The photo of the skier shown in Figure 7.2 was taken with the 1A filter. Does the filter depth weaken enough blue light? No. We can see that the white snow in the photo is still blue. At this time, 8 1A or 85C filter will get better effect.

Let's take a look at a group of photos taken in the shadow of the open air. Figure 7.3 uses 1A filter, and Figure 7.4 uses 8 1A filter. Please carefully compare the skin color in the two photos with the white part of the coat. Suggestion: It is best to use 8 1A filter when shooting in open shadows and high altitude, including mountain scenery, skiing scenery and aerial photography. Conversion filter is also a very common filter in color photography. It allows us to use solar films under tungsten filament illumination or optical films under sunlight illumination. Its advantage is that even if shooting under different types of light sources, there is no need to replace the unfinished film. In addition, we don't have to carry two types of films with us, just one; They usually carry solar films and conversion filters used when shooting in tungsten lamp. Let's take a look at how the conversion filter works and compare its shooting effect. See table 7. 1.

What kind of effect will you get if you shoot with solar film under tungsten filament light? Please refer to Figure 7.9. Among them, the picture 1 is the result of shooting with sunlight film, and the colors of nature are reproduced very accurately. Figure 2 is the result of shooting with sunlight film under tungsten filament light, which is incorrect. From the picture, we can see that the original color is not accurately reproduced in the part with golden and reddish tones. The photo shown in Figure 3 was also taken under a tungsten lamp, and the sunlight film was also used, except that a conversion filter was used. Now there's another problem. What kind of filter should we use? In this regard, you can refer to the instructions provided by the film manufacturer. Generally speaking, 80B filter is used under 3400K light, and 80A filter is used under 3200K light.

Let's look at the reaction of light balance film to different light sources. As shown in fig. 7.9 and fig. 4, it was shot with optical film under tungsten filament light, and B-type color reversal film was used. The photo completely and accurately reproduces the true natural color. The same film is used, but in Figure 5, sunlight is used as the light source, which obviously shows a bluish tone. If we want to shoot with optical film in sunlight (or strong light), we can use conversion filter, typically 85B filter. The photos taken at this time are shown in Figure 6. Comparing Figure 6 and Figure 4, which reproduced color is more accurate? Both photos are well reproduced, but they are not perfect. As mentioned above, if we use color negative film, we can further adjust the color when making photos; And color reversal film can't.

Table 7. 1

Kodak conversion filter

Film genre

light source

Nikko film

Type a

Type b

sunlight

not have

Eighty-five

85B

flashlight

not have

Eighty-five

Not recommended

Photographic astigmatism lamp (3400K)

80B

not have

8 1A

Tungsten filament photographic astigmatism lamp (3200K)

80A

82A

not have