Photography 101: Aperture and Depth of Field Demystified
4309
Arts & Entertainment > Photography
Mar 1, 2007
Jennifer Clarkson
Photography 101: Aperture and Depth of Field Demystified
First, let?s review the three things that directly influence how all photos are captured on both film and digital cameras:
1) Aperture: the lens opening
2) Shutter Speed: the speed of opening and closing the shutter, which determines how long the subject matter stays on the film that comes through the given aperture
3) The speed of the film (a.k.a. ISO setting), which directly influences what choices of aperture and shutter speeds you can use
ISO Setting
Before your camera can detect aperture and shutter speed for a particular subject, it must be told how many worker bees are loaded into the camera (i.e. the film and its corresponding ISO). The more worker bees there are, the less time they need to capture the same amount of light, so the ISO setting directly impacts the aperture and shutter speed settings.
These days, ISO on film cameras is detected by a bar code on the film?s cassette, which the camera reads and then tells the light meter. On digital cameras, you can set the ISO to a particular rating by selecting it in the menu, or leave it on the automatic setting so that the camera decides which ISO speed to use. Once your camera knows how many worker bees it has, it will be able to detect which aperture and shutter speeds are ideal for various conditions.
Aperture
Aperture controls the volume of light that passes through the lens and onto the film. The volume of light is determined by the size of the lens opening (the aperture): big, medium, or small openings. Aperture works in conjunction with Shutter Speed to correctly expose an image. Depending on the lighting conditions (night vs overcast vs sunny), a given aperture will require a different partner shutter speed.
Most cameras recommend these settings automatically for you, assuming you want everything in the photo to be in focus. You can usually opt to set the aperture and have the camera pick an appropriate shutter speed (called aperture-priority), or vice versa (called shutter speed-priority). If ever you want to change the depth of field (i.e. what?s in focus), the aperture-priority setting will come in handy, if not full manual where you set both aperture and shutter speed.
Depth of Field
The term ?Depth of field? simply refers to a picture?s overall sharpness. It is the direct result of the aperture setting on your camera. By setting the aperture (a.k.a f-stop) to a small number ? e.g. f/2.8 ? you are setting the lens opening to be large. Such a ?wide-open? aperture limits the plane or field of focus to be very narrow: this is called a small or narrow depth of field. For example, if you?re photographing a long line of fuzzy ducks extending into the distance, and you only want one duck in the middle to be in focus, then you would open up your aperture by setting it to a small number, such as f/2.8. Once you?ve chosen this setting, your camera will help you figure out the appropriate shutter speed to provide a good overall exposure.
By setting the aperture to a large number ? e.g. f/16, f/22 or even f/32 ? you are setting the lens opening to be very small: this is called a large depth of field. This small aperture allows the camera to focus clearly on things both close and far in the same shot. Continuing on with our fuzzy duck example, using a small aperture will allow you to capture the entire row of ducks in perfect focus. The near duck will be just as sharp as the far duck, as will all the ducks in the middle.
Try it out! Once you?ve focused on a subject, you will notice that there are areas beyond and/or in front of what you focused on that are not sharp. Assuming you want everything sharp, the laws of depth of field say to use a small aperture of f/16, f/22, or f/32. If you instead want a narrow field of sharpness in your image, the laws of depth of field say to use a wide-open aperture of f/2.8 or f/3.5.
In a nutshell, those big aperture numbers - f/16, f/22, f/32 ? render the greatest depth of field or area of overall sharpness and those smaller aperture numbers ? f/2.8, f/4, f/5.6 ? render a minimal area of sharpness beyond or in front of what you have chosen to focus on. Again, depending on lighting conditions, different shutter speeds will be required to expose the image correctly.
Caveat for digital photographers:
These depth of field rules and example f-stops were created for those using 35mm format cameras, and you will find reference to them all over books and the internet. Digital cameras are typically closer to 38mm format, and will thus have better results narrowing their aperture (so as to get everything in focus). The claim to fame of digital cameras is to have excellent focus from near to far - infinity and beyond, but in doing so have limited ability to capture narrow focus. For example, f/2.8 on a typical digital camera will not be a large enough aperture to narrow your depth of field sufficiently to only get one fuzzy duck in focus. DSLR owners can simply purchase a macro lens to do this, but digital point & shoot owners may not have the capability to narrow their depth of field noticeably. Best to stick to landscape shots!
1) Aperture: the lens opening
2) Shutter Speed: the speed of opening and closing the shutter, which determines how long the subject matter stays on the film that comes through the given aperture
3) The speed of the film (a.k.a. ISO setting), which directly influences what choices of aperture and shutter speeds you can use
ISO Setting
Before your camera can detect aperture and shutter speed for a particular subject, it must be told how many worker bees are loaded into the camera (i.e. the film and its corresponding ISO). The more worker bees there are, the less time they need to capture the same amount of light, so the ISO setting directly impacts the aperture and shutter speed settings.
These days, ISO on film cameras is detected by a bar code on the film?s cassette, which the camera reads and then tells the light meter. On digital cameras, you can set the ISO to a particular rating by selecting it in the menu, or leave it on the automatic setting so that the camera decides which ISO speed to use. Once your camera knows how many worker bees it has, it will be able to detect which aperture and shutter speeds are ideal for various conditions.
Aperture
Aperture controls the volume of light that passes through the lens and onto the film. The volume of light is determined by the size of the lens opening (the aperture): big, medium, or small openings. Aperture works in conjunction with Shutter Speed to correctly expose an image. Depending on the lighting conditions (night vs overcast vs sunny), a given aperture will require a different partner shutter speed.
Most cameras recommend these settings automatically for you, assuming you want everything in the photo to be in focus. You can usually opt to set the aperture and have the camera pick an appropriate shutter speed (called aperture-priority), or vice versa (called shutter speed-priority). If ever you want to change the depth of field (i.e. what?s in focus), the aperture-priority setting will come in handy, if not full manual where you set both aperture and shutter speed.
Depth of Field
The term ?Depth of field? simply refers to a picture?s overall sharpness. It is the direct result of the aperture setting on your camera. By setting the aperture (a.k.a f-stop) to a small number ? e.g. f/2.8 ? you are setting the lens opening to be large. Such a ?wide-open? aperture limits the plane or field of focus to be very narrow: this is called a small or narrow depth of field. For example, if you?re photographing a long line of fuzzy ducks extending into the distance, and you only want one duck in the middle to be in focus, then you would open up your aperture by setting it to a small number, such as f/2.8. Once you?ve chosen this setting, your camera will help you figure out the appropriate shutter speed to provide a good overall exposure.
By setting the aperture to a large number ? e.g. f/16, f/22 or even f/32 ? you are setting the lens opening to be very small: this is called a large depth of field. This small aperture allows the camera to focus clearly on things both close and far in the same shot. Continuing on with our fuzzy duck example, using a small aperture will allow you to capture the entire row of ducks in perfect focus. The near duck will be just as sharp as the far duck, as will all the ducks in the middle.
Try it out! Once you?ve focused on a subject, you will notice that there are areas beyond and/or in front of what you focused on that are not sharp. Assuming you want everything sharp, the laws of depth of field say to use a small aperture of f/16, f/22, or f/32. If you instead want a narrow field of sharpness in your image, the laws of depth of field say to use a wide-open aperture of f/2.8 or f/3.5.
In a nutshell, those big aperture numbers - f/16, f/22, f/32 ? render the greatest depth of field or area of overall sharpness and those smaller aperture numbers ? f/2.8, f/4, f/5.6 ? render a minimal area of sharpness beyond or in front of what you have chosen to focus on. Again, depending on lighting conditions, different shutter speeds will be required to expose the image correctly.
Caveat for digital photographers:
These depth of field rules and example f-stops were created for those using 35mm format cameras, and you will find reference to them all over books and the internet. Digital cameras are typically closer to 38mm format, and will thus have better results narrowing their aperture (so as to get everything in focus). The claim to fame of digital cameras is to have excellent focus from near to far - infinity and beyond, but in doing so have limited ability to capture narrow focus. For example, f/2.8 on a typical digital camera will not be a large enough aperture to narrow your depth of field sufficiently to only get one fuzzy duck in focus. DSLR owners can simply purchase a macro lens to do this, but digital point & shoot owners may not have the capability to narrow their depth of field noticeably. Best to stick to landscape shots!
Article Source: http://www.articlerich.com
Jennifer Clarkson is a Canadian photographer living in Ottawa. For a full explanation of digital camera features and more information about what amateur buyers need to know, please visit her website at www.jclarksonphotography.com Article Submission made possible by: www.articles-submit.com Courtesy of:ArticlesRus.Net
Write a Review
Add to My Favorite
Refer it to Friend
Report Article
Other links owned by this user
Shutter Speed, simply put, controls the speed at which the camera?s lens opens and closes. It works in conjunction with film speed (a.k.a. ISO) and aperture (lens opening size) to correctly expose an image. By using the Shutter speed priority setting on
Category:
What is a Memory Card? A card is a storage device commonly used by digital cameras to write digital photos. It is a mechanism to store your photos, and later transfer them to computer for processing and printing. Essentially, a
Category:
Typical humans see their world in 16 "f-stops", or measurements of light reflecting off their environment. Cameras ?see? no more than 5 stops at once. So the more contrast there is in the scene, the more stops of light there are to BE seen. This
Category:
The term ?white balance? originates from e world of video imaging where a device (waveform monitor) was used to match or ?balance? e signals from e camera?s red, green, and blue channels to make accurate whites under various lighting conditions,
Category:
First, let?s review te tree tings tat directly influence ow all potos are captured on bot film and digital cameras: 1) Aperture: te lens opening 2) Sutter Speed: te speed of opening and closing te sutter, wic determines
Category:
Most humans see the world in living colour, but did you know that your camera?s light meter does not? Then how does it capture photos? Does it see the world in black and white? No! When your camera left the factory, it was calibrated to see the world as
Category:
Waterfalls often make great subjects of photos, but it?s very easy to get a bad result if you?re not paying attention when you click the button. Here are the top 4 mistakes photographers make, and the easy ways to improve your
Category:
So you've decided to buy a camera - congratulations and welcome to the land of Photography! Now how do you figure out what camera is right for you? The first thing you have to decide is whether you want a digital camera or a film camera. This article
Category:
Other links at Arts & Entertainment > Photography
It can be hard work locating the perfect field of poppies in front of the perfect view of a Tuscan town. You think it might just be easier to slap in a field of poppies on your computer at home later. Well, these days it is a viable alternative, one
Category:
Digital and film photography are far more alike than they are different, but digital image recording opens up many new, valuable and perhaps unanticipated opportunities.
Category:
Photography is the art of light and shade. A photo is basically a record of the light conditions at a certain period in time and space. That is why the lighting plays a very important role there.
Category:
You can crop the photos to remove unnecessary background images and focus on the subject of the picture itself. You can also adjust the contrast, brightness, and colors to make the photo more eye-catching and appealing. Removing red eye is also possible w
Category:
Photographs are a means to capture moments of this world. In reproduction or printing of these photographs, lab calibration is an important factor to be able to get prints of the best integrity.
Category:
Site Sponsor
Directory Statistics
Articles: 68214
Categories: 501
Yahoo Entertainment
