Cameras. A glimpse into a meaningful memory at a moment's notice, capturing the emotion, scenery, and ambiance of a road trip or the awe instilled by Niagara Falls. Since 1816, we have used cameras in order to immerse our posterity in the nostalgia instilled by more distant memories. How do these wondrous machines capture such a crisp image and what role does light play in the phenomena?
Film cameras are dependent on the use of a plastic laced with various silver, light-sensitive chemicals. The film is wrapped in a cylindrical fashion in order to protect the film and placed inside the camera. Once you press the button on the camera, a shutter system is activated to open an aperture on the front of the camera. Light can then enter through the lens and onto the film, beginning a series of chemical reactions to store the image.
The film has to be filled before you can develop it, which is typically conducted within the confines of an automated machine. The film is removed and immersed in developing fluid for the pictures to initially appear. However, these pictures would appear dark in areas where the photo had a lot of light, and vice versa. These negatives are used to print the finished versions of the photo.
The issue of using film is that when you need to capture one moment, you cannot print it out until you fill the entire roll of film. This can be a particular nuisance since it would already take days to develop the film and receive it through the mail. A common—and preferable—alternative to film cameras are digital cameras.
Digital cameras work in a completely different mechanism from the classic film cameras. Similarly, pressing the button opens the aperture for light to enter. Either a charge-coupled device (CCD) and or CMOS image sensor processes the light rays as electrical signals. Light from the object you're photographing hits the sensor chip, dissipating it into millions of pixels, converting photons to code.
The CCD/CMOS image sensor of digital cameras functions by a grid system. When an image is presented, they store the details in a grid of squares, measuring the color and brightness of each pixel. The details are then stored in a sort of binary code, stringing millions of characters for one image alone. Compression remediates this issue by squishing the images in order to save memory by using fewer numbers in the code. You've probably heard of different methods of storing images as JPG files. The higher the image's resolution, the more memory is occupied.
In every way, digital cameras prove to be superior to film cameras. Conversely, the annual sales of cameras have decreased in tandem with the rise in sales of smartphones, most of which have a built-in quality camera. The size and quality of image sensors are vital in comparing the validity of purchasing a camera versus using a smartphone. Simply put, while smartphones claim to have clearer images—harboring 13 megapixels in an imaget—the smaller sensor chip handicaps the resolution in comparison to the digital cameras.
Now, I have been babbling about the mechanisms that govern the utility of cameras, but one thing shared among each type is the information taken in by light, one of the most fascinating phenomena in physics. Learning its characteristics could help you manipulate it to create beautiful images.
The picture above was taken on a trip of mine to Governor's Island in New York City. It was a fairly rainy day and this one location, surrounded by brick buildings and luscious trees, had a lake-like puddle commandeering the walkway. The picture appears to be edited with two overlapping images varying of opacity. In truth, the only editing I did was change the filter to create a lime green color in the trees. I took advantage of specular reflection in order to create a surreal ambiance in the photo.
When light travels in a medium, such as water, some light reflects back at a fixed angle. In still water, the light would come in contact at what's called an angle of incidence and reflects back at an angle of reflection. These two angles are congruent and tangent to one another. A normal line can be drawn to differentiate the two angles. While some of the light reflects back, other light passes through via refraction.
The light would refract in an angle complementary to the angle of incidence (meaning they sum to 90 degrees.) The speed of light (3.0 x 10^8 m/s) stays constant even when it travels through the water, yet the frequency of the wave may vary. Simply by abusing the reflection of light, I was able to take a stellar image.
And how does refraction play a role? Since some of the light passes through the water surface, it reaches the concrete and is absorbed, hence why the light reflected is an image that has a lower opacity. The background image is simply the concrete floor, giving a nice texture to the background.
Another cool thing about light is that it is the fastest thing in the universe. They always follow the quickest path—which isn't always the fastest. Imagine there is a muddy path and an asphalt plank. Typically, a diagonal path would be the shortest path, but the quickest would be a balance between spending the least time in the mud as well as traveling the shortest distance. If you were to take a circle and trace its path, a cycloid curve forms.
Following that arc length with respect to gravity and force would produce the quickest path. Imagine the mud was water, the asphalt was a vacuum of air, and you were light. Light follows this algorithm in tandem to this dilemma, called the Brachistochrone Paradox. There's a video explaining how mathematically possible this curve is if you are interested.
Overall, imaging and light are two phenomena, synergizing the manmade with the natural to preserve what we find special. The snippets of memories and expression are preserved by using light and technology to our manipulation. I feel that this is one aspect at which we've tamed the fastest thing in our universe in order to always have those moments that give meaning to our lives.
