Black and white film development - density

Density refers to the amount of silver that accumulates on a certain portion of the film. If a lot of silver accumulates, this part becomes a black area, and there is very little light that can pass through, then this part is a part with a high density; if there is only a little accumulation of silver, it is a part that is more transparent, then the light passes through. It is easy, this part is called the thin part of the film. The density on the film is from the completely light-transmitting portion, that is, the portion with the least silver-density density to the almost completely light-impermeable high-density portion. This range is called the density range. Since the image of this film is the opposite of the image in the final photograph, the low density on the film becomes black on the photograph, and the dark part of the film on the film becomes white.

The transparent part of the film is that very little silver halide is converted to metallic silver, while the opaque part of the film is that most of the silver halide particles are converted into metallic silver 7 . Between these two extremes, there is a series of different densities on the film. This is the detail of all the images produced by this density range.

The term “density” is also used to indicate the density of the entire film. The density of the full film is nearly opaque to the entire film. Some parts are denser than the other, but they are not thin. There are many places on this film. The accumulation of metallic silver.

At the other extreme of the film is the thin film. In the thin film, all the parts are relatively transparent. Some parts are slightly denser than others, but most of them are relatively transparent because the metal silver is very thin everywhere on the thin film. less.

Generally speaking, you always want to make such a negative film, that is, it is not very dense, nor is it a very small density, that is not too thick and not too thin, but in the middle, we will call this kind of film Normal density negatives. Now let's look at different density negatives and discuss how to deal with them.

Normal density negatives

When you expose your film normally and develop it normally, you should get a normal film with a series of densities of various sizes inside it, but there are no areas that are too thin or too thick to print in detail. From this kind of film you can get a picture where the details can be clearly seen, from the brightest highlight to the darkest shadow, which is what you often want to achieve, that is, to get a normal film .

The film is too thick

Observe this negative to see how it differs from a normal negative. This negative is almost completely opaque. If such a negative is printed, it will require a much stronger exposure than the normal negative when printed. Get photos that appear to be normal. There are also several incidental effects that increase the granularity that can be seen and the loss of various shades of shading that cannot be separated by the proper level. These two effects are an incidental effect that we do not want. When the film is too thick, this will happen. Second, if it takes a very long exposure time to print a photo that is more normal when printing a photograph, there is a danger of baking the film badly, and it will warp because it is baked for too long.

If a film is too dense, it is often due to overexposure, sometimes due to over development or both, both overexposed and underdeveloped. If your film is often too dense, you have to press the following Check it out. l. Check if your exposure meter is accurate. Do you use the exposure meter in the correct way?

Do you develop with the correct development temperature and correct development time? A higher temperature will make the developer too active. An additional problem due to the high density is that the particles increase in size as the density increases, especially if the density is too high due to excessive development, especially the backsheet is grainy, that is, the particles are too thick. If the film is due to overexposure, it can still have quite fine particles unless overexposure is accompanied by over development.

Film is too thin

Look at the difference between this film and the normal and thick film. The film is completely transparent. The printed image has only a few details in the shadow. There are also few details in the middle tone. It and the normal film The obvious difference is the lack of a clean and clear tone level that is typical of normal negatives.

Thin film is due to underexposure or underdeveloped, or it may be due to the lack of both, in the end is that the fault depends on the contrast of the film.