مصدر الضوء في المكبر .. كتاب التحميض والطبع والتكبير

The source of the light in the magnifier:

It is usual for us to use Tungsten lamps in magnifiers, the power of which ranges from 60 to 100 watts for most of the usual purposes. It is possible to use ordinary lamps that were originally prepared to work with a current whose electrical voltage is less than the electrical voltage that is actually available, and also suitable for these special purposes are those very bright lamps known as Photo flood lamps, which usually do not last longer. Some amplifiers are also equipped with high-pressure mercury vapor lamps, which are characterized by their low consumption of electric current and their relatively low temperature despite the increase in the amount of light they emit. Mercury vapor lamps are not suitable in case of using Variable Contrast Paper, as its spectral sensitivity is not compatible with the spectral characteristics of the rays emitted by these light sources, and it is easy to build an amplifier. Type by using the same camera that we use, whether it is small (6 x 9 cm for example) or large (30 by 40 cm) and you see in the form of 65, for example, for this type of means of enlarging images .. This is from some difficulties may arise if I want to enlarge pictures in places Remote areas devoid of electric current, and this usually happens on exploration trips or scientific missions in places far from urbanization. Here, it is permissible to use a continuous electrical current (.D.C).

It is emitted by batteries such as those used in vehicles with lamps similar to the headlights in the vehicle, but then it is expected that the degree of contrast will increase a lot (due to the narrow point from which the light is emitted from inside the lamp) and therefore it may be necessary to place an opaque white glass in front of the light source . Although this glass ensures the distribution of light and the reduction of contrast, it also causes a decrease in the optical energy that is used for the magnification process. Here, the lack of light energy can be overcome by using a lamp with an electric voltage that is about 10% less than the electrical voltage that we use (and this also means a shortening of the lamp’s life, as we mentioned in the margin of the previous page).

It was common in the past to enlarge images with the help of daylight. Some amateurs (with limited capabilities) still follow this method until now. It may be followed by necessity in places that lack electricity (such as working in rural homes or in remote places, for example), and enlarging in this way does not require any special devices or the camera that you use and without the need for an optical capacitor (Fig. 11).