8 min
Chemistry of Film Cameras Chemistry Connections
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- Education
Hopewell Valley Student Podcasting NetworkChemistry ConnectionsThe Chemistry Behind Film CamerasEpisode #12 Welcome to Chemistry Connections, our names are Riya Mishra and Summer Wang and we are your hosts for episode #12 called the Chemistry Behind Film Development. Today we will be discussing what makes film cameras, such as Polaroids, or Canon Cameras, work.
Segment 1: Introduction to Film CamerasIn this episode, we’re going to be talking about how film is developed, and the chemical processes which occur every step of the way. Thanks to inventor and scientist Edwin H. Land, people can enjoy the look of a film picture without having to go through the process of developing film. Picture dark room photography, the low lights, the chemicals, and the long-long process before you get your photos. Now imagine that condensed into a tiny camera, weeks of work can be completed in a minute. This popular camera, made by popular companies like Polaroid and Instax provides a physical, and tangible memento in an instant. It seems like magic… but it’s all chemistry.
Segment 2: The Chemistry Behind Film Cameras
When you hit ‘click’ on your camera, how does the photographic film develop on an atomic level? Firstly, it’s important to know that film is covered in a crystalline solid, usually a silver halide (so silver and a halogen). The most popular choice for film is silver bromide (AgBr). When photons from light come into contact with one of the grains, an electron is ejected from the valence levels of the bromine atoms, and onto the conduction band of the crystal. Then, the electron combines with a moving silver ion, and makes atomic silver. When this occurs multiple times, a clump of silver metal is produced. That atomic silver creates dark areas on the paper due to its color. The colorless ion Ag+ gains an electron to form solid silver. This seemingly simple reaction creates the dark colors that you see in your pictures. The formation of silver metal is directly proportional to the intensity of light. This may sound confusing, but it means that more light hitting the film means that area will appear darker when the film is developed. So, if anyone ever tells you to keep your picture in the dark as it develops, you know why.
For non-instant film cameras, once the picture is taken, film must be placed in a developer, or a chemical liquid which makes the concealed image on the film eventually visible. Developer itself can be chemically altered to adjust the rate at which the film develops-mainly with the usage of developing agents. Without developing agents, the process of film development could take hours, or even days! But, with some developing agents, like potassium hydroxide (KOH), this process can be sped up. You see, for film to develop at the quickest rate possible, the developing solution should have a pH between 10-11. This is a pretty high pH, meaning there needs to be a way for film developers to reach that pH without interfering with other parts of the developing process. KOH happens to be an extremely strong alkali, or a strong base. When KOH is added to the film, it produces an alkaline solution on top of the film. This raises the pH, bringing it...
Hopewell Valley Student Podcasting NetworkChemistry ConnectionsThe Chemistry Behind Film CamerasEpisode #12 Welcome to Chemistry Connections, our names are Riya Mishra and Summer Wang and we are your hosts for episode #12 called the Chemistry Behind Film Development. Today we will be discussing what makes film cameras, such as Polaroids, or Canon Cameras, work.
Segment 1: Introduction to Film CamerasIn this episode, we’re going to be talking about how film is developed, and the chemical processes which occur every step of the way. Thanks to inventor and scientist Edwin H. Land, people can enjoy the look of a film picture without having to go through the process of developing film. Picture dark room photography, the low lights, the chemicals, and the long-long process before you get your photos. Now imagine that condensed into a tiny camera, weeks of work can be completed in a minute. This popular camera, made by popular companies like Polaroid and Instax provides a physical, and tangible memento in an instant. It seems like magic… but it’s all chemistry.
Segment 2: The Chemistry Behind Film Cameras
When you hit ‘click’ on your camera, how does the photographic film develop on an atomic level? Firstly, it’s important to know that film is covered in a crystalline solid, usually a silver halide (so silver and a halogen). The most popular choice for film is silver bromide (AgBr). When photons from light come into contact with one of the grains, an electron is ejected from the valence levels of the bromine atoms, and onto the conduction band of the crystal. Then, the electron combines with a moving silver ion, and makes atomic silver. When this occurs multiple times, a clump of silver metal is produced. That atomic silver creates dark areas on the paper due to its color. The colorless ion Ag+ gains an electron to form solid silver. This seemingly simple reaction creates the dark colors that you see in your pictures. The formation of silver metal is directly proportional to the intensity of light. This may sound confusing, but it means that more light hitting the film means that area will appear darker when the film is developed. So, if anyone ever tells you to keep your picture in the dark as it develops, you know why.
For non-instant film cameras, once the picture is taken, film must be placed in a developer, or a chemical liquid which makes the concealed image on the film eventually visible. Developer itself can be chemically altered to adjust the rate at which the film develops-mainly with the usage of developing agents. Without developing agents, the process of film development could take hours, or even days! But, with some developing agents, like potassium hydroxide (KOH), this process can be sped up. You see, for film to develop at the quickest rate possible, the developing solution should have a pH between 10-11. This is a pretty high pH, meaning there needs to be a way for film developers to reach that pH without interfering with other parts of the developing process. KOH happens to be an extremely strong alkali, or a strong base. When KOH is added to the film, it produces an alkaline solution on top of the film. This raises the pH, bringing it...
8 min