المرشحات والوان الطيف .. كتاب فن التصوير الفوتوغرافي

Filters and spectrum colors:

You can control the colors entered into the film by using filters of different colors, by deleting colors and adding or strengthening other colors in the image as you wish. Take the color red, for example. When you shoot without a filter with a black and white film, a red subject, you will get the subject in a dark gray color in the film. And if you want to make it appear lighter, all you have to do is use a red filter, as it has the property of preventing colors other than red from passing through it, or limiting their passage to varying degrees depending on the density of the filter, and because a lot of red light has affected the film, the red subjects become in The film is so dense that it is difficult for the light of the enlarger to penetrate it when printing, which leads to its appearance being light in the print

final. The same thing happens when using any other filter of any color, as it makes subjects with the same filter color appear lighter in the final print. And if you want it to appear darker, that is, in a more intense gray form, you must use the filter with the complementary color: and this is what brings us back to the composition of the added color. To find the complementary color of red, for example, we have to mix the other two primary colors: blue and green, so the result is dark blue.

Thus, by using a cyan or cyan filter, we can make the red subjects look black in the final print.

Now, to understand how much you can control the colors in the image, we offer you the following: If you are going to photograph two cars, one green and the other red, use the red filter and you will get a bright red car in the final print, while the green one will appear almost black or blackish . Photograph the two cars using a green filter and you will get the opposite result.

The yellow filter does not have the same properties as the other filters, as it tends to have properties of its own. For example, the two filters that are light yellow and medium dark reduce the violet and blue colors in the visible spectrum. Try the yellow filter in a scene that contains a large amount of sky with scattered pieces of clouds. Shoot without a filter, then with a filter and compare the results. The sky in a print captured without a filter will appear white, not vibrant, and clouds will disappear or appear very light

Look at the print captured with the filter now and notice the huge difference between the two prints. The blue sky appeared darker and the scattered clouds appeared quite clearly in the sky, which led to a print that is incomparable in terms of quality compared to the first print. Although panchromatic films are affected by all colors, we find that the yellow filter when used with these films gave additional results. enjoyable

for photos. As this filter works to show the color gradations in a vibrant way, highlighting the subtlest differences between them. And if you want to touch what you say yourself, try photographing a face with a yellow filter and without a filter, and you will see the difference.

As the face with the filter will get accurate, vibrant details that match reality

In short and as a general rule:

If you want to reduce color in a black and white image, use a filter with the same color as the subject. If you want to darken the color, use the complementary filter for the subject color

The following table helps you to distinguish between uses of filters

- Corrective filters are light-colored filters (light yellow, medium yellow, dark green, light green, and medium blue). 2- Contrast filters are the filters with darker colors than the previous one (orange - red - dark green).

Contrast filters have more interesting effects than correction filters. You will notice the difference if you repeat the previous experiment and take a picture of a landscape with a correction filter, then with a contrast filter. You will find that the contrast filter in the image taken with it made the sky look dark with white clouds scattered here and there like cotton cloth

Filter factors:

As mentioned above, filters are distinguished because they “stop” the effect of certain colors from reaching * the film. And this effect is not limited to those colors only, as the overall color intensity decreases in the scene when a filter is used, and therefore a sufficient amount of light does not reach the film slice, which leads to an underexposed image if you do not remedy the matter by compensating for the lost amount of light. Filters give each filter a specific number that indicates the amount of missing light and the amount of light that must be compensated. This number is called the filter factor. For example, you find numbers on some filters such as (A2X) and this. That you must allow twice as much light to pass through the lens to compensate for the missing light as a result of using the filter - you remember, no doubt, in the first chapter of this book that we said that to increase the amount of light entering the lens twice, you have to open the lens or decrease the speed, i.e.

Shutter by one stop

Suppose the exposure meter gives you a reading of f-16 at 1/125 second and you need to use a medium yellow filter that has a filter factor of 2x. Here you find

You have two options: either adjust the aperture to f11 or adjust the shutter speed to 1/60 sec depending on what is most important in making the shot - whether depth of field is more important or stop motion is more important.

Certainly not all filters have the 2x factor, as some have a 3x or 4x factor or more, and here the compensation will increase according to the factor written on the used filter.

At the end of our conversation about filters, we advise you to pay attention to them and not to expose them to dust or scratches, as they are of inestimable importance and benefit.

Example of light passing through a filter

Translator: The above applies to the use of discrete counters or implicit counters of non-TTL type. As for the exposure meters through the TTL camera lens, the missing amount of light is automatically compensated as soon as the filter is placed on its holder in front of the camera lens, and the photographer must confirm that the meter is chosen for the desired value only.