Assessing the Quality of Developed Negative

Once dry, we will carefully study the negative to observe it's characteristics and possible defects. Although a definitive test of the negatives quality is a positive print, were we will be able to appreciate the sharpness and quality of the image much better, the negative at plain view provides a lot of information. A developed negative has to be examined as closely as slides. In these, the low latitude requires a lot of precision in the exposure: and error in the exposure value is fatal; the same mistake, made in a negative, can be corrected when printing. Nonetheless, the maximum quality of a black and white image is also achieved when no mistakes are made.

•  General density: According to the exposure theory the predominant density can't be excessive or insufficient, although a high general density is preferable to a low density in the entire roll. If the whole roll has insufficient density (large loss of detail in the shadows, medium density lights), and the numbering of the film appears with normal density, we have made a general underexposure error (mistake in the photometer, wrong sensitivity). On the other hand, if the scarce density also affects the numbering, we have made a mistake of underdeveloping (because of contamination or insufficient temperature, concentration or time). On the other extreme, a high general density, with absence of transparent zones in the shadows of the whole roll, is due to a general overexposure if the numbering appears with normal density, or an overdeveloping if the density of the numbers is also high.

A correctly exposed and developed negative is always predominant in medium densities. An unjustified excess of high or low densities in all the roll indicate we are using the film or developer incorrectly, and we are not fully taking advantage of the emulsion.

•  Contrast : If the brightness scale we want to register is translated to a different density scale then we are right with the exposure value. If we are missing lights or shadows, we have used an adequate exposure value for the main zone, but not for the brightness interval of the scene, because we have placed it on a point of our density ladder that doesn't correspond to what we wanted to do.

•  Veil level: The minimal density of the emulsion, which we have called "transparent" until now, corresponds to a null exposure level (borders of the film) (4.1.2). In normal conditions, the minimal density is null, and the density of those zones on the negative is equal to the density of the base of the acetate base of the film, which can include a slight mask or tone. If in the deep shadows of the image or in the border of the film we can appreciate a certain density with no detail, the emulsion has acquired a noticeable density or veil , which is equal to a reduction in contrast. A veil is produced if the emulsion has been exposed to light (cracked camera, darkroom, black bag or barrel), a too energetic or forced developing, which can cause the formation of silver even on unexposed zones, as with a defective fixing.

•  Unequal density in a same image: vertical lines of great density indicate that the cartridge was exposed to a very strong light (frequently, when loading the camera or spiral). Lower magnitude variations are a symptom of irregular developing, because of contamination or excessive concentration or temperature of the developer, because of insufficient agitation or because of contact of the emulsion with a surface during developing.

•  Spots: The film, even when dry, attracts dust with a static electricity charge. When it is moist, the dust particles can stay stuck. Maximum cleanliness is necessary in the interior of the camera, the developing barrel, and the place were negatives are stored. Also water may contain impurities that make the use of a filter recommendable.