The Relationship Between Camera Function and the Laws of Optics, Research Paper Example

Abstract

The field of physics and the study of optics have helped to expand the knowledge of explaining the aspects of light, and how motion is able to travel through time and space. Optics is essential to how people view different things. Not only with optical instruments, but in explaining the vocabulary of how our eyes functions in reality. For this paper in looking into the subject of optics, this paper is tasked with researching how a camera works. While many people understand the basic functions on how to operate a camera, this paper will look deeper using a physics’ lens to interpret how a camera is able to work as an optical instrument. In doing so, this paper will provide the reader with an advanced comprehension of both optics and the world of physics.

Introduction

In the field of physics, there are a plethora of subfields that examine how light travels through space and time, which explains a variety of natural processes, such as how rays from the sun hit the earth. Physics is one of the oldest academic fields and it allows us to determine the influence of objects on light, which causes phenomena such as refraction and reflection. One subfield of physics, optics, studies the properties and behaviors of light. Of particular importance is how light interacts with instruments, such as with the lenses of a camera. This paper will explore how the camera works by describing mechanics related to the field of optics. The discussion will focus on how camera optics are impacted by aperture, the focal length, and the law of reciprocity.

Optics Explained

Optics is a branch of physics that revolves around the nature and uses of light. It is particularly concerned with the systems used to develop pieces of plastic or glass to create the lens, which alter the light that passes through it. Because of optics, cameras, telescopes, microscopes, and movie projections are available for our use. Optics has been an essential component of the technological and scientific process. As optical fibers, lasers, mirrors, and lenses have been used to create copy machines, weapons targeting systems, and to enhance computing processes. The Greeks provided some of the earliest insight with regards to the nature of light, concluding that light rays are reflected from at object at the same angle that it strikes the surface at (Wolfe, 2007). From these school of thought, many societies began to understand the ability of lenses to capture rays of light. The field of optics begin to steadily grow throughout the Middle Ages, as many scientists published treatises on lenses and mirrors, examined the various properties of prisms and lenses, and the magnifying properties, although they did not examine the nature of light itself.

The invention of eyeglasses led to the development of concave lenses in the 1400s in Italy. This was the beginning of the establishment of the field of optics. At this time, a technique known as camera obscura was formed that is reminiscent of the modern camera. This was a darkened room with a pinhole pierced on one side where a convex lens would be inserted. The lens would be able to project the image it sensed from the pinhole to the wall of the room, where it could be viewed or traced on paper. Modern cameras are considered to be miniature versions of this early technique. However, the image is now recorded by a sheet of film that is coated with light-sensitive chemicals or a range of electronic components instead of being traced by hand.

Modern optics began with the invention of the compound microscope, which functioned as a combination of magnifying glasses, helping people see things that could not be viewed with the naked eye. Magnifying lenses were continually being improved to allow for higher magnifications that aided in the discovery of microorganisms by scientist Antoni van Leeuwenhoek in during the 17^th century (Wolfe, 2007). Perfecting this technology paved the way for discoveries that would make the modern camera effective. For example, through this understanding, Galileo was able to discover the law of refraction (Snell’s law) that gave way to the understanding of geometrical optics needed in the scientific design of eyeglasses, telescopes, microscopes, and other optical devices. Polarization and double refraction were also soon discovered in which aided in the observations of Jupiter and the moon, which helped in understanding the velocity of light. These contributions to the beginning of optics ultimately contributed to the development of the camera that we are familiar with today.

The camera was invented in the 1820s, used mainly by hobbyists, and consisted of glass plates coated with light-sensitive chemicals to produce permanent photographs. At this point, the camera structure was large, which required it to be mounted on a tripod. In discussing the aspects of cameras and photography, we must understand the role that optics plays. Optics presently is divided into two categories, physical optics and geometrical optics. In which physical optics includes relativistic optics, quantum optics, the interactions of light with matter, color, light as an electromagnetic phenomenon, and wave optics. While geometrical optics consists of ignoring the quantum nature and wave nature of the behavior of light. Cameras, as well as microscopes, telescopes are designed using geometrical optics. The camera that was developed in the 1820s in addition to many chemical based cameras that are used today follow this same principle.

According to Wolfe, “cameras are described in terms of their optical speed, exposure time, resolution, and secondarily by versatility, size, weight, and price” (Wolfe, 2007, p. 49). With regards to optics, cameras are able to harness visible light and produce visual images through manipulation. Cameras are an optical instruments that are made up of curved mirrors and lenses that are designed to focus light in numerous ways. A photograph is just a point projection of a three-dimensional image, which is known perspective. The camera lens itself is the center of this perspective. Photography works similarly to how we view objects using our eyes. For a camera used in photography, the optics perspective consists of both the medium that the electromagnetic radiation is recorded, and the lenses, the medium can consist of a charge-coupled device, film, or a plate. In understanding the relationship between optics, cameras, and photography, the user must consider the reciprocity of the shot and the camera that is followed in this formula: Exposure ? ApertureArea × ExposureTime × SceneLuminance. This means that the length of time will be increased, which permits more light to enter the system making the aperture smaller, giving it a greater depth of focus that can lead to blurriness when motion occurs. Ultimately, the law of reciprocity measures the camera’s aperture and the focal length.

Photography

The quick spread of the computerized camera and PC since the 1980s have made it possible for individuals in industrialized social orders to catch, alter, and offer pictures all the rapidly and affordably than was possible with the film camera. Photography is one of the greatest inventions of all time because it has significantly altered the world. It gives us a way to record history or to keep track of important moments in our lifetimes. Despite the importance of the camera, the science behind it is somewhat basic. The main difficult that many amateur photographers have is that they must align the lens with their subject so that they can record a fresh, unmistakable picture. Clarity can be improved using the manual SLR camera. According to by David Goldstein, “the particle nature of light by looking at the variation in color and light level from pixel to pixel when the sensor is illuminated by a uniform source, the user is seeing the differing number of phone counts” (Goldstein, 2009). According to Carr (2001), there are two relevant characteristics of a digital camera, including the spatial and the ability for light to pass through the lens. The image will consist of pixels that represent, “the intensity of the frequency (color) of light falling on its detector (photo-electric cell)” (Carr, 2001, p. 2) the relationship of these concepts is that they follow the laws of physics to produce images using technology and science.

How Cameras Work

A camera lens (otherwise called photographic target or photographic lens) is an assembly of lenses or optical lens utilized in conjunction with a camera body and instrument to make pictures of articles either other media or photographic film equipped for storing a picture artificially or electronically. There is no real distinction on a basic level between lenses used in microscopes, telescopes, video cameras, or still cameras although the development of these products differ. On a fundamental level, a basic curved lens will suffice. However, a compound lens made up of various optical lens components is obliged to correct the numerous optical abnormalities that emerge. According to Wolfe, “the essential elements of a camera are an aperture stop, a means for forming an image, a shutter, and a recording medium” (Wolfe, 2007, p. 48). As a result, a few abnormalities will display in any lens framework. It is the responsibility of the lens fashioner to correct to perfect the image. Common rectilinear lenses are considered “enhanced pinhole lenses”. As demonstrated, a pinhole “lens” is basically a little opening that squares most beams of light, in a perfect world selecting one beam to the article for every point on the picture sensor. There are a few limitations to pinhole lenses. The mechanics is broken down in this image and explanation (Leyden Science, n.d).

“1. Light reflects off the object being photographed.
2. This light reflects off the object in all different directions and hits the lens from different angles.
3. The lens focuses these rays of light to a point behind the focal point forming a real image.
4. The film is placed at the point where the real image is projected to.
5. The shutter temporarily moves from in front of the film and allows light to hit the film.
6. Light hits the film causing chemical reactions which “expose” the film.
7. The shutter then closes, and finally the film is advanced so an unexposed piece of film is ready for the next picture.” (Leyden Science, n.d).

A pinhole camera with an extensive opening is blurry despite the fact that every pixel is the shadow of the aperture stop. Making the pinhole smaller enhances determination, yet diminishes the amount of light captured. “The aperture is usually determined by an adjustable iris near the front of the lens system. It controls how much light can enter the system” (Wolfe, 2007, p 48). Once contracting the opening reaches its limit, it will not enhance the determination any longer. Past this point, making the opening smaller makes the picture blurrier and darker. Practical lenses can be considered as a response to the inquiry “in what capacity would we be able to alter a pinhole lens to give a smaller spot size and admit more light?” This could be resolved by placing a convex lens at the pinhole with a central length equivalent to the separation of the film plane. This permits the user to significantly open up the pinhole, with beams striking the focal point of the lens going directly through it.

When dealing with photography, cameras, and optics, it is important to consider that the use of the camera relies on the law of reciprocity or photography reciprocity, which describes the inverse relationship between the duration of light and the intensity that results from the light-sensitive material reaction. The law of reciprocity states that, the response of the film will be a result of the defined intensity multiplied by the time, to find the total exposure. Therefore in the optical density is determined by the decreased duration of exposure and the increased light intensity. Furthermore, the relationship between aperture and shutter is described by the law of reciprocity. This becomes evident when manipulating the camera to achieve the perfect exposure, in which the correct level of light is obtained by the increase and decrease the aperture, until the correct level of light is observed. This can be enhanced by doubling the shutter speed, which adjusts the amount of light coming into the camera. This law is important for photographers to understand so that they are able to capture blurry free pictures in addition to avoiding under or over exposing their images.

Furthermore, photographers should consider that many different types of glass are used to develop lens components and that these materials can be used to create differential effects. The most common material used is glass because it has excellent optical properties and is resistant to scratching. Imperviousness. Other materials that have been used for this purpose include, but are not limited to, meteoritic glass, germanium, Plexiglas, other acrylic plastics, fluorite, and quartz glass. Plastics permit the assembling of unequivocally aspherical lens components which are troublesome or difficult to produce in glass. This is important because these features enhance the lens assembly process and contribute to better performance. However, plastics are typically used only to create the cheapest cameras because plastic scratches easily. To enhance the quality of the image produced by the camera, many lenses are used in conjunction with concave mirrors, in which an image is created when the scene is placed behind the focal point of the mirror. Furthermore, the use of convex mirrors places the focal point behind the mirror, so that the light is parallel to the principal axis that reflects away from the focal point. This is similar to what an image in a polish doorknob would look like. Convex lenses, similar to convex mirrors, use the principle of refraction in order to manipulate light. For lenses, there are two consecutive refractions from the glass back and from air to the glass. A camera works as a single-lens camera and compound-lens system in which uses the laws of refraction and reflection to project an image.

For many years, the cheapest disposable cameras have utilized molded plastic lenses and have procured a terrible notoriety for their low image quality. However numerous current, elite, and costly lenses produced by prominent camera makers incorporate formed or mixed aspherical components. This demonstrates that not all lenses made with plastic components are of low photographic quality. A lens will regularly have an opening alteration system, such as an iris diaphragm, that will direct the measure of light that passes. Historically, cameras achieved this function by using a pivoting slider or plate with distinctive measured gap. A screen meant to control the time in which light may pass, can be joined inside the lens in order to achieve quality images. Cameras that implement these systems can range from homemade to digital or standard. However, each version of this product is expected to consist of the elements that allow for images to be generated using the pinhole perspective and the elements of physics and optics.

Conclusion

The development of cameras started back in the 16^th and 17^th century with the creation of the camera obscura, the pin-hole systems that allowed scientists to project images to walls. Science has refined this technology to make better use of light refraction, and these improvements are included in many of the cameras that are sold on the market today. The most important component of the camera, the lens, is used to create the real image that viewers see. Harnessing this light in different ways allows the photographer to generate clear images in his or her work. Optical instruments are beneficial for the purpose of improving image quality. Ultimately, to understand how cameras work and to become the perfect photographer, it is necessary to understand how cameras work. The relationship between optics and camera functionality is important due to the implications it has on allowing individuals to achieve success using this art form.

Works Cited

Carr, J.R. “Using a digital camera to teach the physics of light.”  Frontiers in Education Conference. 2001. Print. 10.1109/FIE.2001.963669

Goldstein, David. “Physical Limits in Digital Photography” Northlight Images. 2009. Web. 11 March 2015. www.northlight-images.co.uk/downloadable_2/Phys ical_Limits_2.pdf.

Harris, Tom. “How Cameras Work.” How Stuff Works. 2013. Web. 11 March 2015. http://www.howstuffworks.com/camera.htm

How Does a Camera Work? (n.d). Leyden Science. Retrieved from http://www.leydenscience.org/physics/electmag/camera2.htm

Rossi, M., Gratton, L.M., Oss.S. “Bringing the Digital Camera to the Physics Lab.” Phys. Teach. 51, 141. 2013. Web. 11 March 2015. http://scitation.aip.org/content/aapt/journal/tpt/51/3/10.1119/1.4792005

Wolfe, William L. Optics Made Clear: The Nature of Light and how We Use it. SPIE Press. 2007. Book.