Resolution of a photogram

Unlike the traditional photographic process, where a photographic negative is enlarged, the photogram is usually a contact print, where the information is printed directly from the original matrix to the light sensitive paper at a ratio of 1:1. Because of this, photograms have exquisite resolution and detail - there is no film grain.

However good a film is, it only has the ability to resolve a certain amount of information per square cm. A frame of  35 mm film for instance is enlarged about 58 times to make a 8x10 print and the grain of the film which has recorded the tonal variations of the subject is also enlarged. This is why many photographs look grainy. A 8x10 photogram on the other hand only has the very fine grain of the paper, which is unperceivable to the naked eye, to inhibit the clarity of the image. 

A photogram made on 10x8 inch paper for example will show a much greater resolution than an 8 X10 Inch print from a 35mm negative - any fine lines and textures contained in the object can be revealed by the process.

This work  is an example of a combination photogram/photograph from the  Codes of Survival project. The central image is from a 35 mm frame while the photogram border is a contact print.   The section on the right is an enlargement of the area with the red line around it and demonstrates the difference in grain between the photograph and the photogram.