How instant photography works

In this blogpost I am going to tell you how instant photography works. 

Basically, it can be said, that instant film follows the same principles as regular camera film. Patterns of light are captured on a plastic-based film which is covered with a light sensitive silver compound. These light sensitive silvers produce a latent image, which becomes visible during the developing process. The difference to regular camera film is that instant film already contains all the chemicals needed for developing the photograph.

The whole film is organized in layers. All these layers with the chemicals and the light sensitive silver compounds inside are attached to a black base layer. The bottom layers are the three light sensitive layers, sensitive to blue, green and red light respectively, and the developer layers containing the dye couplers. On top of these bottom layers, there lies the reagent layer.The reagent is a mixture of chemicals, which later triggers the chemical reactions. Before a photograph is taken, the reagent layer is empty and the reagent sits in the white frame, separated from the picture to prevent it from developing too early. On top of the reagent layer there are three more layers with chemicals. These are the image layer, the timing layer and the acid layer. All these layers are concealed by clear plastic on the very top. A regular colour instant film, therefore, consists of up to 15 different layers.

While taking an instant photograph, various reactions happen at the different layers of the instant film. Once you press the trigger, the instant film is exposed to light for a short moment, causing the light sensitive layers to react.The photograph then is ejected from the camera. It passes between two stainless steel rollers which spread the reagent evenly over the reagent layer. This is the start for several chemical reactions.

The reagent is a mix of different chemicals causing the other chemicals in the different layers of the instant film to react. First of all, it prevents the light from filtering on to the light sensitive layers below, so they will not react anymore. Secondly, the reagent causes the developer layers to release their dye couplers. The dye couplers then react with the different colour layers and move to the image layer, where the image is captured. On top of the image layer lies the timing layer. Its only purpose is to slow down the reagent on its way to the acid layer, giving the image time to develop. The top layer, the acid layer, clears up the particles in the reagent that prevented the light from filtering through.

When we look at an instant photograph and it seems as if it was developing right there infront of our eyes, what we actually see is just the last step. We only see the acid layer dissolving the last particles, so that the image becomes visible for our eyes.

Analysis of Instructions

We looked at these instructions on how to make a camera lucida and rated how helpful we thought they were. 

At first sight, these instructions on how to build a camera lucida seem to be chaotic. We think this is mainly because they do not look like the instructions we are used to. Clearly numbered steps which would make it much easier to follow are missing completely, let alone an explicit list of materials needed to build the camera lucida. The reader has to figure out all this on his own. Even though these instructions do not follow the classic rules of how instructions should look, they still contain all the necessary information. The drawings, for example, indicate the needed materials. By combining the information from the drawings and the additional instructional texts, it should be possible to build a functional camera lucida based on these instructions. In retrospect, the instructions would need some work without doubt, but yet we have to admit that they turned out more helpful than expected at first glance.

Description of the Photograph "Migrant Mother"

The photograph portrays a middle-aged migrant mother with her three little children, all four of them with gaunt bodies. Clad in worn-out and dirty clothing, their outer appearance indicates a difficult life. At the bottom of the picture an infant is lying on the mother’s lap with its head resting on her left arm, where its face is half-hidden from the camera. The two older children have turned away from the camera. On the right side of the picture one child is clinging to its mother’s shoulder and burying its face in her neck whereas the one on the left side tries to hide itself behind the mother’s shoulder. The center of the photograph is occupied by the mother who is exuding an aura of sadness. Her worn and weather-beaten face bears witness to everything she has gone through. All her worries are apparent in the deep lines that furrow her face. The whole photograph leaves the observer with a strong feeling of sympathy, rooting for a better life for the mother and her three little children.

Dorothea Lange "Migrant Mother"