أثر طبيعة الطبقة الحساسة على قوة التحديد .. كتاب الإضاءة والفلم

The effect of the nature of the sensitive layer on the strength of determination:

The nature of the sensitive layer has an effect on the strength of determination similar to its effect on the size of the particles, and we can summarize this as follows:

(a) Slow-sensitivity films with small grains help to obtain a greater limiting force, for example, a limiting force of 120 millimeter lines can be obtained, while this strength does not exceed 60 millimeter lines for the fast film (33 shis, for example).

(b) Thin films in which the thickness of the gelatin layer is reduced, which are called Thin Coated Emulsions, in which light diffusion decreases during imaging and helps to increase the strength of determination.

(C) The higher the transparency of gelatin, the lower the optical diffusion in it, thus increasing the strength of determination.

(d) Films prepared with an anti-halo layer in which the determination strength increases.

The effect of exposure on the power of determination

We must bear in mind that all the factors that affect the construction of the image and turn the latent image into a negative visible image, have an effect on the power of determination. The properties of the show solution have a great influence on the strength of determination in the sensitive layer. Show solutions that lead to fine grain developers increase the strength of determination, and vice versa, the strength of determination decreases when using bleach solutions that penetrate into the layers of gelatin, and in this last case the resulting defect can be reduced by increasing its concentration while reducing the duration of the show, thus reducing its penetration into the layer If the exposure time is increased, the result will be worse than if the solution was diluted.

Surface developers have no significant effect on increasing the defining strength of slow-sensitive films, as they themselves lead to fine grains, but this effect may appear if the use of the surfactant solution is accompanied by a decrease in the exposure time of the film to light. And as an explanation of the effect of each of the surface blemishes and deep buffs on the fixing power of the sensitive layer, the following is mentioned: When the film is placed in the buffing solution, the buffing mechanism takes place according to one of the following two forms:

(a) Reduction either begins in the superficial upper layer of flagella and then gradually permeates within all thicknesses of the sensitive gelatinous layer. This is what Surface Development is all about.

(b) Or the reducing agent begins its effect throughout the thickness of the sensitive layer all at once. This is what is called Depth Development, and the reduction factor has a great impact in determining the type of display mechanism.

1- There are fast-acting reducing agents such as metol and paraminophenol. One of their characteristics is that they begin their work as soon as the solution comes into contact with the surface of the sensitive layer, so they immediately begin to build up the image with an acceptable density before the solution penetrates into the entire thickness of the sensitive layer.

2- There are other slow-acting reducing agents (such as hydroquinone) that require a period of time in principle to start working. During this period of time, the solution has penetrated all the thicknesses of the sensitive gelatinous layer, and thus the reduction begins in all of this thickness at once. The degree of blackness in the superficial parts of the gelatin is almost equal to the deep parts of it, so building the image then does not start only from the surface layer, but rather starts from both the deep and superficial parts of the gelatin together at the same time.

As we have already learned that the light rays falling on the film do not stop their effect on just the point on which the rays fell, but rather spread through the thickness of the sensitive layer (Fig. The film will be more sharp, assuming that the rendering process has been stopped at the right time, while the deep-impact solutions penetrate a lot into the thickness of the sensitive layer, so the silver salts are reduced in the areas affected by this indirect light diffusion, so they are reduced, so the sharpness of the image is greatly reduced. In the same way, it seems to us also the importance of solutions with a surface effect in the effect of the optical halo. It is clear from this that the power of analysis. Resolution is greatly affected by the type of reducing agent and the composition of the display solution.