US2757091A - Photographic developer - Google Patents

Description

United States Patent PHOTOGRAPHIC DEVELOPER Isaac Oretzky, New York, N. Y.

No Drawing. Application July 22, 1954, Serial No. 445,190

2 Claims. (Cl. 95-88) The present invention relates generally to the art of photography, and in particular it relates to an improved fine grain developer of photographic film.

In the art of developing photographic film, it is highly desirable that the same developing solution be capable of use for films exposed under widely diverse conditions. Ordinarily, the developer must compromise between developing speed, life of solution, and proper image characteristics, i. e., shadow detail, contrast, grain size. To these compromises must be added the sacrifice of overexposed and under-exposed film.

The prime object of this invention is to provide a developer capable of developing badly under-exposed pictures in a roll of film without adversely overdeveloping pictures in the roll taken at proper exposures.

Briefly stated, this invention comprises a specific developer formulation capable of carrying out the foregoing object.

Using this developer the speed of photographic film is increased from 12 to 20 times, depending upon the nature of the light. In natural light under the most adverse conditions, e. g. during a cloudy late afternoon, when the exposure meter with the slide out registers in the lowest blocks, this developer will have the elfect of increasing the speed of the film about 12 times. Under artificial (tungsten) light, the speed is increased up to 20 times or more. This characteristic is most advantageous when a series of pictures taken on a roll of film include several taken outdoors in natural light and others taken indoors under limited light (such as provided by ordinary house lamps). All the pictures will be developed into usable negatives. Thus the substantial differences in lighting facilities available during the shooting of a sequence of pictures on a single roll of film are largely equalized if the exposed film is handled in the developing solution of this invention. The weakest latent image will be brought out without simultaneously burning a strong image.

The specific formulation of the developer is as follows:

This developer is very stable and does not deteriorate. It will keep at least one year to one and one'half years in a stoppered bottle. A solution of developer which has already been used will nevertheless be stable and usable for about eight months. One quart of the developer can 2,757,09l Patented July 31, 1956 ice develop about fourteen standard rolls of film approximately eighty inches each.

While the above formula produces the best results, it will be understood that some of the ingredients listed may be replaced by other chemicals. For example, benzoic acid can be used in a place of sodium bisulfite without affecting the quality of the developer. In place of the glycin, para-amino-phenol hydrochloride could be used. However, glycin has the quality of providing a desirable staining effect to the developer and is a better preservative.

The developing period which produces the most favorable results is 911 minutes at room temperature, e. g. The developed negative is clear and sharp, and is capable of enlargement up to 19 times without occurrence of strong or disfiguring grain. Under optimum conditions of uniform temperature in the developer, the short stop and the hypo; and a drying time of about 30 minutes the negative can be enlarged 20 times without showing objectionable grain. Film which is overdeveloped, i. e., left in the developer too long, will nonetheless not be mottled or disfigured. The grain Will be quite fine and uniform, and unobjectionable.

Following is a specific example of the results produced by this developer. Two pictures were taken under artificial light on Kodak Super XX Film at one-tenth of a second exposure with a lens opening of F 5.6. The light consisted of an overhead 150 watt bulb suspended from the ceiling at a location about 13 feet from the subject, and a watt bulb in a shaded lamp. The exposure meter registered nothing. When developed, each picture came out with full clarity and fine grain.

In addition to having much faster development time than the presently available fine grain developers, the present developer produced negatives having much better detail and much sharper, clearer images. Whereas this invention has been described in detail with respect to a specific embodiment thereof, it is to be understood that various changes may be made therein on the basis of the teachings hereof, by those skilled in the art, without departing from the protective scope of the following claims.

Having thus described the invention, What is claimed is:

1. A photographic developing composition containing the following ingredients in the following proportions:

Maximum Minimum 1. 96 2. 196 160 3. 7 3 4. Hydroquinone gr 150 55 5. Glyein (parahydroxyphenyl glycine). g.. 14 4 6. Sodium Carbonate 322 75 7. Acetone 644 8. Triethan0lamine. 644 155 9. Water to make one-half gallon so 2. A photographic developing composition containing the following ingredients in the following proportions:

No references cited.

Claims (10)

1. A PHOTOGRAPHIC DEVELOPING COMPOSITION CONTAINING THE FOLLOWING INGREDIENTS IN THE FOLLOWING PROPORTIONS:

1. ELON GR 150 96

2. SODIUM SULFITE G 196 160

3. SODIUM BISULFITE G 7 3

4. HYDROQUINONE GR 150 55

5. GLYEIN (PARAHYDROXYPHENYL GLYCINE) G 14 4

6. SODIUM CARBONATE GR 322 75

7. ACETONE GR 644 155

8. TRIETHANOLAMINE GR 644 155

9. WATER TO MAKE ONE-HALF GALLON SOLUTION.