البلورة السالبة ( The Negative ) .. كتاب فن التصوير الفوتوغرافي

The negative crystal

A negative crystal is not a target in itself, we need it to get an image, so the only value of a negative crystal is the possibility of getting a good image of it, and its appearance matters only because it may tell us whether it will give a good image or not.

The best test for a negative crystal is to print it on ordinary photographic paper No. 2 2 ° N. If it results in an image with healthy contrast, clear high light areas, and deep, rich shadows, then the negative crystal is good. In addition, if the negative is thin enough, the exposure time for printing is short, and the negative is therefore excellent.

How do we judge the advantages of a negative crystal?

It is difficult to judge a negative crystal, and say whether it has been shown, and then shown successfully. But there are some rules that help in judging a negative crystal.
To judge a negative crystal, look through it, not at it. Hold it and direct it towards a scattered light source, and look at the light source through it. Seeing bright light through the crystal means that the image printed from it will be devoid of light details, while seeing dim light means that the details are light and will not appear in the print.

The simplest type of Negative Viewer consists of a safe light filter, and on it is a sheet of sparkling opal glass (Picture 6). The negative crystal on it appears to be of little density if it was displayed and then appeared well, as some details appear. In places of shadows, and places of high light appear semi-transparent. The image that appears on the binoculars (photo 6) is an image that has been displayed and appears well.

Here we can say a word to explain the difference between Density and Contrast in a negative crystal. Density means here: the amount of silver fixed on the crystal. If the black on it is thick and dark, then the crystal is dense, but if the crystal is almost transparent, then it is thin or low in density.

Contrast is the intensity difference between the lighted places and the shadowed places on the crystal. This means that the crystal can be of contrast in both cases, a dense crystal and a thin crystal that is not sufficiently dense. Pictures 7 to 12 illustrate this point.

The negative crystal that is underexposed appears less dense than normal, and the places of shadows in it are either completely transparent, or have a faint image that does not appear in the print. The negative crystal that appears in an imperfect endorsement is also light and has little density, but the details of the places of shadows in it are normal. In general, you can differentiate between an insufficiently exposed crystal and an underexposed crystal by examining the places of shadows in them: In an underexposed crystal, the shadows are empty. As for the crystal that lacks endowment, the shadows appear normal, the details are almost, but their density is deficient.

The overexposed negative crystal looks dense, and the overexposed crystal also looks dense, and you can differentiate between the two cases by examining the shadows in both.

Table No. (1) summarizes the above information, and the relationship between the degree of exposure and endorsement and the appearance of the negative crystal.