Exposure and Depth of Field for Photography - Coursework Example

DEPTH OF FIELD TABLE OF CONTENT 1.0 Table of content 2.0 Introduction 2.1 Depth of field 2.2 Circle of confusion 2.3 Aperture control 3.0 Rules of depth of field 3.1 Reference 3.2 Bibliography INTRODUCTION The human eye varies in its ability to perceive sharpness depending on each individual. Depth of field is a concept that depends on this ability to register when a point is sharp and when it is not. In a photograph, the distance that is perceived to exist between the nearest and the farthest objects captured in the photo is referred to as the Depth of Field (DOF). It is determined by the subject magnification at the sensor plane and selected lens aperture (Langford, 2000). It varies depending on a variety of factors. In photographs, the areas in the depth of field tend to have a sharp appearance. On the other hand, those that are beyond or in front of the depth of field appear blurred. DEPTH OF FIELD When there is a need to obtain a sharp image, a large DOF is recommended. In cases where there is a need to create emphasis on a particular subject, a smaller DOF will prove more effective in the process; it will deemphasize the foreground and the background in the photograph. Merklinger (1992) made a suggestion that, in order to be clearly recognised, distant objects need to be much sharper. This sharpness is achieved by focusing beyond the hyper focal distance. Close objects however, are large on film thus there is no need for sharpness. The depth of field is affected by; subject matter, distance between the camera and the subject, movement during the exposure, lens focal length, circles of confusion, and format size. CIRCLE OF CONFUSION In reference to depth of field, circle of confusion refers to how much a point needs to be blurred in order to be perceives as not sharp. In a case where it can be perceived by the eye, the region is said to be outside the depth of field thus, not sharp. The opposite is true in a case where the spot cannot be perceived by the eye. Ralph et al. (2000) points out that the circle of confusion is used to determine the depth of the field. In real lenses, not all rays are perfectly focused; even at the best of focus, a point may be imaged as a spot. This leads to the creation of a circle of confusion which is the spot a lens can produce. The region on the image where the spot is less than the resolution of the eye forms the depth of the field. Circle of confusion in an original image depends on three factors the first one being the visual acuity. This is the closest possible viewing distance. Secondly, we have the viewing conditions which are dependent on the viewing distance. The enlargement of the original image to the final image also has an effect on the circle of confusion formation. APERTURE CONTROL In the control of the depth of the field, the size of the circle of confusion on the camera’s sensor is determined by the size of the aperture, the lens focal length, and the distance from the subject. A large aperture has a smaller f-stop number, when its focusing distance is close it serves to produce a shallow depth of field. Therefore, short focal length lenses, small apertures, and long distance between the lens and the subject all contribute to an increase in the range of sharp focus. In contrast, long lenses coupled with wider apertures and short distance between the lens and the subject result in decrease in the depth of field (Ray, 2002). RULES OF DEPTH OF FIELD There are three rules that determine the depth of field (Ralph et al., 2000). The first one states that larger apertures cause narrower depths of field. This means that an increase in the size of the aperture will increase the depth of field, thus a smaller portion of the image formed will be in focus. A small aperture will result in a deeper depth of field and more of your image will be in focus. Secondly, it depends on the distance. Closer subjects cause narrower depth of field whereas, when the photographer is further away, the depth of field will be higher. The third rule states that cameras with larger sensors give more blur with a given focal length and f-number. The shorter your focal length, the higher your depth of field, for example, with a 4mm lens the depth will be immense. CONCLUSION Photography is a skill that requires a lot of understanding to master. There is need for understanding the relationship between the actual act of taking of a photograph, and the factors involved; depth of field, circle of confusion, aperture and the rules that aid in the production of quality photographs. REFERENCE Langford, M. 2000. Basic photography. 7th Ed. Oxford: Focal Press ISBN 0-240-51592-7 www.books.google.com>Photography>Techniques>Equipment Merklinger, H. M. 1992. The ins and outs of focus. Seaboard Publishing (Paperback). www.amazon.com/../B00A5JSHCT Ralph, E. J., Sidney, F. J., Geoffrey, G. A. & Norman, R. A. 2000. Manual of photography: A textbook of photographic and digital imaging. 9th Ed. London: Focal Press www.books.google.com>Photography>Techniques>General Ray, S. F. 2002. Applied photographic optics. 3rd Ed. Oxford: Focal Press ISBN 0-200-51574-9 www.amazon.com>Books>Arts&Photography>Photography>DigitalPhotography BIBLIOGRAPHY Dallmeyer, T. R. 1892. On the choice and use of photographic lenses. London: Jarrold Printing www.ieeexplore.ieee.org/iel5/5308791/53... George, C. 2006. Total digital photography. Running Press Book Publishers. ISBN 978-0-7624-2808-3 www.barnesandnoble.com Sheppard, R. 2010. Digital photography: Top 100 simplified tips & tricks. 4th Ed. John Wiley and Sons ISBN 978-0-470-59710-1 www.robsheppard.com Sheppard, R. 2010. Landscape photography: From snapshots to great shots. John Wiley and Sons www.robsheppard.com TABLE OF CONTENTS 1.0 Table of content 2.0 Introduction 2.1 Process of exposure 2.2 Shutter speed 3.0 Aperture 3.1 ISO 3.2 Conclusion 3.3 Reference 4.0 Bibliography EXPOSURE 2.0 INTRODUCTION The process of creating long-lasting images by recording of light is known as photography. In photography, the ability to create quality photographs depends on a variety of factors. These factors have to be understood and taken into consideration in order to perfect the skill of photography. 2.1 PROCESS OF EXPOSURE Exposure is the technical process of recording of light. This is done by exposing of the film or imaging sensors in digital cameras to light in order to make a conversion of light into a photograph. Peterson (2004), states that the correct exposure achieves the best effects. Overexposure leads to production of photos that have loss of highlight detail. This means that the important bright parts of the photo will appear to have been washed out. On the other hand, underexposure leads to loss of shadow detail, the important dark areas will have a muddy appearance (Sheppard, 2010). In the process of exposure, there are three important factors and these make up the exposure triangle. They include; the ISO, Shutter Speed, and Aperture. The triangle is a simple illustration of the relationship between the components and, alteration in any of the components will trigger changes in the other two. When there is effective control of all three, excellent photography and production of quality photos is achieved. It is therefore important to make a detailed study of these components. 2.2 SHUTTER SPEED The Shutter speed is also known as the exposure time. This is the length of time during which the camera’s shutter is open (Sydney, 2000). During this duration, the light is recorded onto the recording device. Its main role is to determine the amount of light that reaches the sensor. Apart from that, it causes a change in the appearance of motion in a picture; short shutter speeds freeze fast-moving objects whereas, long ones blur moving objects. This brings about an artistic effect in the photograph depending on the photographer’s desired outcome. Shutter speed is measured in units of exposure value known as stops. If the light available is not enough, a slower shutter speed will be needed in order to achieve a good exposure. Conversely, when more light is available a faster shutter speed will be needed for the same effect. Camera shake or the movement of the camera during exposure may result in the creation of blurry images. This can be prevented by the use of a flash or improvement of the ambient lighting. A flash is used to produce artificial light which helps in broadening the scope and enhancing appearance of the subject (Lee, 2000). Other ways of ensuring quality images is by getting close to the object as well as light sources in a case where a flash is not used. A photographer can also; lean up against the wall, kneel, sit, or take a position that does not cause strain on the body. 3.0 APERTURE The second component is the Aperture. This is the opening of the lens allowing flow of light that is being recorded. It is usually represented by an f-stop ranging from f/1.0 to f/22 and above (Ralph, 2000). A larger aperture means a smaller f-stop and vice versa. A small f-stop means the aperture is large thus allowing more light into the camera onto the recording device. Less time will thus be needed in exposure of the image. In contrast, a large f-stop means the aperture is small thus limiting the amount of light flowing onto the recording device. More time will be needed in exposure of the image in this situation. In relation to the Shutter speed, a larger aperture will call for faster speed whereas; a small aperture will call for a slower shutter speed. 3.1 ISO Langford (2000), states that ISO is the sensitivity of the film to light, or the sensitivity of the image sensor in the case of a digital camera. Its representation is by numbers where higher numbers denote greater sensitivity. Greater sensitivity requires less light to record whereas; lower light sensitivity requires more light. In film, sensitivity to light is affected by the size of grains of silver halide. An increase in their size causes an increase in sensitivity. In photography these grains are depicted as noise in the photos taken (Ray, 2002). The use of film and digital recording differ in a number of ways. Photos taken by film cannot be edited to suit various purposes whereas; those taken digitally can be edited after exposure. Photography using a film camera doesn’t require a lot of power and can last long even on small batteries, digital camera batteries however need to be charged frequently. Factors shared by both include; the resolution depends on the quality of the lens in the camera and both are affected by noise and grain which is evident in the photos taken. 3.2 CONCLUSION In conclusion, it is possible to capture a wide range of life’s experiences on camera. In order to do this right and create magical memories in form of photographs, the photographer must master the skill of photography, taking into account all the aspects involved in the production of quality photographs by use of a film or digital camera. 3.3 REFERENCE Langford, M. 2000. Basic photography. 7th Ed. Oxford: Focal Press ISBN 0-240-51592-7 www.books.google.com>Photography>Techniques>Equipment Lee, F. 2000. The complete guide to night and low light photography. New York: Amphoto Books ISBN 0-8174-5041-6 www.google.com>Photography>Techniques>Lighting Peterson, B. 2004. Understanding exposure: How to shoot great photographs. New York: Amphoto Books 3rd Ed. www.digital-photography-school.com/unde... Ralph, E. J., Sidney, F. J., Geoffrey, G. A. & Norman, R. A. 2000. Manual of photography: A textbook of photographic and digital imaging. 9th Ed. London: Focal Press www.books.google.com>Photography>Techniques>General Ray, S. F. 2002. Applied photographic optics. 3rd Ed. Oxford: Focal Press ISBN 0-200-51574-9 www.amazon.com>Books>Arts&Photography>Photography>DigitalPhotography Sheppard, R. 2010. Digital photography: Top 100 simplified tips & tricks. 4th Ed. John Wiley and Sons ISBN 978-0-470-59710-1 www.robsheppard.com 4.0 BIBLIOGRAPHY Dallmeyer, T. R. 1892. On the choice and use of photographic lenses. London: Jarrold Printing www.ieeexplore.ieee.org/iel5/5308791/53... George, C. 2006. Total digital photography. Running Press Book Publishers. ISBN 978-0-7624-2808-3 www.barnesandnoble.com Sheppard, R. 2010. Landscape photography: From snapshots to great shots. John Wiley and Sons www.robsheppard.com Read More