تكبير الصورة على الورق الحساس الأبيض وأسود بواسطة المكبر ٢_a

Enlarge a negative with medium contrast, we use paper with a medium gradation or contrast such as number 2 or 3. But this is mainly down to the effect you desire. When analyzing the negative to find out the best gradation of the sensitive paper, do not confuse the intensity with the contrast and look under the selection of the negative. In general, an exposure test can be done on a slide of medium contrast sensitive paper (No. 2 or 3) and then choose the paper gradation for the final image according to the test result.

and all that . . It is preferable to use paper with a glossy surface to obtain accurate details, and matte paper if you want to make frills or repairs in the image, and coarse Silk in the case of enlarging the image of faces to hide the grains. It is up to you and the effect that you want to show, as well as due to the taste of the owner of the image.

Sensitive paper should not be exposed to safety light for a long time, so as not to cause a light haze that spoils the paper. The sensitive surface can be known in the dark by being more sticky to wet fingers, but be careful not to touch the sensitive surface with your fingers except from the edges only that will be outside the scope of the image «in the white frame, otherwise you will find a picture of your fingerprints after acidification because the fatty acids on the surface of the skin prevent the appearance from interacting with sensitive surface.

E - Adjust the zoom ratio:

It is preferable to make marks on the column of the magnifier for the height of the magnifier head when enlarging for different sizes of sensitive paper that you prefer. For example, the size of a postal card, 13 x 18 cm, or 20 x 25 cm, etc. Thus, it will be easy for you to raise the head of the magnifier to the appropriate height for the size of the paper, and after that it remains to adjust the focus of the magnifier lens. Many of the zoom devices have numbers on their columns for height as well as for the zoom ratio, especially for a lens

The name of the lens that is used to enlarge 35mm films and the 80mm lens that is used to enlarge

Movies 120 them. . Now adjust the height of the magnifier to cover the area of ​​the paper you will use. Turn off the light! kindle light magnifier

6- Focusing:

The purpose is to obtain sharp image details. This is done by changing the distance between the lens and the negative, depending on the type of amplifier, either by moving the bellows or by turning the lens.

The focus and the pupil of the lens are set at its largest width to facilitate vision, for example an aperture of 2.8 F or 3.5 F, and the focus is set on white paper of the same thickness as the sensitive paper that you will use (an old, invalid photo can be used and the photo is set on its back.

This paper is placed in the holder of the sensitive paper so that we can determine exactly where the image is located when you put the sensitive paper in the dark.

You can adjust the focus with the naked eye, but in the magnifications, despite the large ones, you may need help. This may be done by using a small manual lens, but the best thing is to use a focus controller of the type that enlarges the grain of the image. And if the negative is very existing and you find it difficult to adjust the focus, you can use a light negative and focus on it, then reposition the list, or use an old negative after a wound or scratching its sensitive surface with a needle and adjust to the image of the wound. negative.

After confirming the accuracy of the focus setting, and determining the location of the image fall by adjusting the position of the sensitive paper holder, remove the paper used in the adjustment without moving

Paper holder Turn off the light of the magnifier and close the aperture of the lens to the required aperture for magnification, which is usually F8, then put the red filter under the lens of the magnifier.

7- Exposure adjustment:

By this we mean exposing the sensitive paper to the light of the magnifier after it has been permeated by negativity. And this process takes place in the dark, and this process is the most important stage in black and white magnification. Most of the problems come from lack of perfection because the sensitive paper does not have the tolerance for latitude films. The exposure must be set exactly to get a good picture, and the negative is an intermediate stage to get a good picture. Thus, we can to some extent fix its defects during the enlargement. As for the image on the sensitive paper, it is the final result, and the defects that appear in it are not easy to treat, and we often have to re-enlarge again.

Exposure depends on several factors that must be fixed as possible in order to make it easier for us to deal with the remaining variables. These variables are:

1- The power of the amplifier bulb: This is almost constant. Unless we change the bulb. 2- Sensitive paper bill: This can be installed using a specific type of paper

Constant manufacturer

- Aperture of the magnifier lens: this we can specify for each magnification ratio so that. It gives us a time for the exposure between 10-20 seconds (a time that allows us to shade and burn and does not allow the negative to stretch. We often use an intermediate aperture around F8.

- Zoom ratio: This can be determined in relation to several sizes that we prefer, for example

Postal card size or 20 x 25 cm.

E - Negative Density: This cannot be fixed, but we can adjust the exposure in the camera and of course the acidification. Thus, we find that most of our negatives are of medium density.
In general, it is preferable, when starting to learn to enlarge, to use medium-density negatives in order to gain sufficient experience

6- Exposure time: This is the variable by which we can, with changing the lens aperture, control the amount of light falling on the sensitive paper to compensate for the variables in negative intensity and zoom ratio, but always try to range this

The time is between 10-20 seconds.

After this theoretical introduction, let's get to work:

Exposure begins with an experiment on a slide of sensitive paper. In complete darkness, take a sheet of sensitive paper that you will use. And cut it or cut it into long strips about 2.5-3.5 cm wide. It is about 10-12 cm long.

Take one of these slides and place them on the base of the magnifier within the scope of the image. Light the magnifier lamp to make sure that an important part of the image falls on the paper slide through the red filter (the paper is not sensitive to red).

Turn off the magnifier light and move the red filter away lens on
Expose the experiment slide

He covered four-fifths of the paper slide with a large piece of cardboard the width of one-fifth visible to the magnifier light for 32 seconds. Reveal five second.

And display the fifty visible to the light of the magnifier for 16 seconds. Reveal a third fifth and display the visible three-fifths to the magnifier light for 8 seconds: Reveal a fifth

Fourthly . Show the four-fifths visible to the magnifier light for 4 seconds: reveal the slide

All and display the entire slide to the magnifier light for another 4 seconds. In this way, we find that the paper slide has five regions that took different exposures, as follows:

64 seconds - 32 seconds - 16 seconds - 8 seconds - 4 seconds.

With a hole after exposing the experiment slide, transfer the slide to the wet section of the dark room. In the event that the wet section is in another room, put the slide in a bag or box that is not opaque to light during transportation. Acid the paper slide and then examine it in bright light. Decide which part is properly exposed. The entire slide may be very light. In this case, repeat the experiment using longer times or a wider lens. . The best exposure may be a medium between two regions, for example, between 16 seconds and eight seconds.. In this case, we can expose the entire sensitive paper for 12 seconds, for example. Turn off the light and place the red filter under the lens. Place the photosensitive paper in the paper holder under the magnifier. Make sure that the entire image falls on the photosensitive paper. Turn off the light and slide the red filter away. Set the timer for the required time (12 seconds for example), then display the paper for this time.

Write down all the experiences you have made. Calculate the time required for a medium-density negative - at the aperture ratios used, and after a while you will find that you can judge the time required for exposure to different negatives with different magnifications.
density
The real test of the validity of the exposure is the response of the sensitive paper to good acidification. The image must be good after acidification in the chemicals suggested by the manufacturer of the sensitive paper for the specified time and temperature. Black, which means that the exposure was a little and should be increased. Conversely, if we find the image appears quickly within seconds in the exposure solution and blackens quickly, then this means that the exposure was too much, and do not think that increasing the exposure time in the first case or decreasing the exposure in the second case is the solution! In the case of overexpression, you will find that the image has become gray haze and yellow spots. In the case of underexpression, we will find that the image tends to be brown with the appearance of spots.

. By changing the acidity, which must not be tampered with

In short, adjusting the darkness of the image should only be done by adjusting the exposure, not |

- Adjusting the colors: we do not need this stage in black and white enlargement, except in the case of using sensitive paper with variable contrast, in which case we use the filter to give us the required degree of contrast (see chapter “sensitive paper”). Appropriate development: see the next section. See beyond