Filed under: Photography
Exposure Guide for Transparency Film
© 1996 Kevin C. O’Neil, Eastern Light Nature Photography, Ltd. All Rights Reserved.
The “System”
This “system” provides accurate exposures guides for the most common lighting situations faced by photographers using transparency film: Normal or Low Light and Bright Sunny Days. This system is not “unique” or “special” in any way. It is the system used by almost all nature photographers (whether they know it or not). Although these guides are generally applicable to print films, because of the wider latitude (i.e., ability to provide proper exposure where the range and contrast of light is great) of print films, the compensation suggestions may not be great enough to provide for proper exposure for print films.
Two Simple Rules
Two simple exposure compensation rules to remember with slide film are “LO-DC” and “LC-DO.”
In Normal or Low Light, and when the tone of the subject matter is Light, you need to Open up to ensure proper exposure. If the subject matter is Dark, you need to Close down to ensure proper exposure. LO-DC means Light Subject, Open Up – Dark Subject, Close Down
On a Bright Sunny Day, and when the tone of the subject matter is Light, you need to Close down to ensure proper exposure. If the subject matter is Dark, you need to Open up to ensure proper exposure. LC-DO means Light Subject, Close Down – Dark Subject, Open Up
These may seem not seem logical at first, but you need to remember that your camera exposure meter is calibrated to properly expose an 18% gray card (a medium tone subject). When you meter a subject lighter than 18% gray under Normal or Low Light, such as snow, the camera meter “tells” you how to expose the snow as if it were a medium tone subject. The resulting image of snow therefore looks gray! When faced with this situation and you are using slide film, you must compensate by opening up 1.5 to 2 stops so that snow is white (i.e., Light/Open).
The opposite is true. If shooting a dark subject under Normal or Low Light, such as a black bear, your meter will give you the proper exposure for an 18% gray card, turning the black bear into a gray bear (or at least a tone of black that is much lighter than the bear actually appeared). Because the subject is Dark, you need to Close down (i.e., Dark/Close).
On a Bright Sunny Day, the rules of exposure shift. Rather than attempt to explain this here, accept it as “truth” and experiment. You’ll be pleased with the results. This exposure rule is often referred to as the “Sunny f/16 Rule.” This means that on a Bright Sunny Day with few clouds in the sky, the proper exposure for a subject with front lighting is f/16 at a shutter speed closest to your ISO film speed. If I was shooting Fuji Velvia (ISO 50), the proper exposure would be 1/60th of a second at f/16, or a combination of shutter speed and f-stop equal to this (i.e., 125th at f/11). One note of caution, always avoid shooting on a Bright Sunny Day unless the subject matter or timing leave you with no alternative. The resulting images are generally not as good as ones taken under better lighting conditions (early morning, late afternoon or on cloudy days).
Filed under: Photography
Exposure Guide for Transparency Film
© 1996 Kevin C. O’Neil, Eastern Light Nature Photography, Ltd. All Rights Reserved.
The “System”
This “system” provides accurate exposures guides for the most common lighting situations faced by photographers using transparency film: Normal or Low Light and Bright Sunny Days. This system is not “unique” or “special” in any way. It is the system used by almost all nature photographers (whether they know it or not). Although these guides are generally applicable to print films, because of the wider latitude (i.e., ability to provide proper exposure where the range and contrast of light is great) of print films, the compensation suggestions may not be great enough to provide for proper exposure for print films.
Two Simple Rules
Two simple exposure compensation rules to remember with slide film are “LO-DC” and “LC-DO.”
In Normal or Low Light, and when the tone of the subject matter is Light, you need to Open up to ensure proper exposure. If the subject matter is Dark, you need to Close down to ensure proper exposure. LO-DC means Light Subject, Open Up – Dark Subject, Close Down
On a Bright Sunny Day, and when the tone of the subject matter is Light, you need to Close down to ensure proper exposure. If the subject matter is Dark, you need to Open up to ensure proper exposure. LC-DO means Light Subject, Close Down – Dark Subject, Open Up
These may seem not seem logical at first, but you need to remember that your camera exposure meter is calibrated to properly expose an 18% gray card (a medium tone subject). When you meter a subject lighter than 18% gray under Normal or Low Light, such as snow, the camera meter “tells” you how to expose the snow as if it were a medium tone subject. The resulting image of snow therefore looks gray! When faced with this situation and you are using slide film, you must compensate by opening up 1.5 to 2 stops so that snow is white (i.e., Light/Open).
The opposite is true. If shooting a dark subject under Normal or Low Light, such as a black bear, your meter will give you the proper exposure for an 18% gray card, turning the black bear into a gray bear (or at least a tone of black that is much lighter than the bear actually appeared). Because the subject is Dark, you need to Close down (i.e., Dark/Close).
On a Bright Sunny Day, the rules of exposure shift. Rather than attempt to explain this here, accept it as “truth” and experiment. You’ll be pleased with the results. This exposure rule is often referred to as the “Sunny f/16 Rule.” This means that on a Bright Sunny Day with few clouds in the sky, the proper exposure for a subject with front lighting is f/16 at a shutter speed closest to your ISO film speed. If I was shooting Fuji Velvia (ISO 50), the proper exposure would be 1/60th of a second at f/16, or a combination of shutter speed and f-stop equal to this (i.e., 125th at f/11). One note of caution, always avoid shooting on a Bright Sunny Day unless the subject matter or timing leave you with no alternative. The resulting images are generally not as good as ones taken under better lighting conditions (early morning, late afternoon or on cloudy days).
Filed under: Graphics 1 & 2
Best Practices for Accessible Flash Design: Part 2
By Bob Regan
Controlling reading order using off stage content
In cases where the application relies on a highly dynamic content, it can be difficult to specify the reading order in advance. In this very small set of applications, it is possible to control the reading order by placing a second set of content off stage in a single column. The on stage content is all rendered as inaccessible to prevent the screen reader from reading it. The second set of content is positioned in a column so the reading order does not jump between unrelated elements.
There are two primary drawbacks to this method. First, it increases the number of objects in the movie, impacting the file size and performance of the movie. Second, users of screen magnifiers may find the off stage content conflicts with the on stage visual content they are working with. Screen magnifiers not only increase the size of elements on the stage, but move them to the center. If the on-stage content is inaccessible, off stage content will draw the focus of the screen magnifier creating a very confusing experience visually. This method is often used in conjunction with screen reader detection, but it is important to consider that users may have both a screen reader and magnifier in use simultaneously.
Screen reader detection
Since this case is intended to benefit screen reader users alone, this method is frequently used in conjunction with screen reader detection. Flash has a unique advantage over JavaScript in that it is able to use MSAA to detect the presence of a screen reader. The method Accessibility.isActive() will return a value of true if a screen reader is present and it is currently focused on the Flash content. It is important that this method not be called in the first second or so in the life of the movie, or it could return a false negative. Rather than calling this method in the first frame of a movie, many designers will attach this method to the first button in the movie.
Building off stage content
If Accessibility.isActive() returns a value of true, the contents on screen are set to be inaccessible. Perhaps the easiest means of accomplishing this is to place all of the on stage content in a single movie clip and then set the .silent property of that movie clip to true. It is preferable to use .silent as opposed to altering the visibility of the movie clip since people relying on screen readers might be working together with a sighted person relying on the on stage content visually.
Next, the off stage content is loaded into a single column. This column need not match the height of the movie. It is important that as changes are made on stage that the off stage content is updated at the same time.
Filed under: Graphics 1 & 2
Best Practices for Accessible Flash Design: Part 2
By Bob Regan
Controlling reading order using off stage content
In cases where the application relies on a highly dynamic content, it can be difficult to specify the reading order in advance. In this very small set of applications, it is possible to control the reading order by placing a second set of content off stage in a single column. The on stage content is all rendered as inaccessible to prevent the screen reader from reading it. The second set of content is positioned in a column so the reading order does not jump between unrelated elements.
There are two primary drawbacks to this method. First, it increases the number of objects in the movie, impacting the file size and performance of the movie. Second, users of screen magnifiers may find the off stage content conflicts with the on stage visual content they are working with. Screen magnifiers not only increase the size of elements on the stage, but move them to the center. If the on-stage content is inaccessible, off stage content will draw the focus of the screen magnifier creating a very confusing experience visually. This method is often used in conjunction with screen reader detection, but it is important to consider that users may have both a screen reader and magnifier in use simultaneously.
Screen reader detection
Since this case is intended to benefit screen reader users alone, this method is frequently used in conjunction with screen reader detection. Flash has a unique advantage over JavaScript in that it is able to use MSAA to detect the presence of a screen reader. The method Accessibility.isActive() will return a value of true if a screen reader is present and it is currently focused on the Flash content. It is important that this method not be called in the first second or so in the life of the movie, or it could return a false negative. Rather than calling this method in the first frame of a movie, many designers will attach this method to the first button in the movie.
Building off stage content
If Accessibility.isActive() returns a value of true, the contents on screen are set to be inaccessible. Perhaps the easiest means of accomplishing this is to place all of the on stage content in a single movie clip and then set the .silent property of that movie clip to true. It is preferable to use .silent as opposed to altering the visibility of the movie clip since people relying on screen readers might be working together with a sighted person relying on the on stage content visually.
Next, the off stage content is loaded into a single column. This column need not match the height of the movie. It is important that as changes are made on stage that the off stage content is updated at the same time.
Filed under: Graphics 1 & 2
Best Practices for Accessible Flash Design: Part 2
By Bob Regan
Controlling reading order using off stage content
In cases where the application relies on a highly dynamic content, it can be difficult to specify the reading order in advance. In this very small set of applications, it is possible to control the reading order by placing a second set of content off stage in a single column. The on stage content is all rendered as inaccessible to prevent the screen reader from reading it. The second set of content is positioned in a column so the reading order does not jump between unrelated elements.
There are two primary drawbacks to this method. First, it increases the number of objects in the movie, impacting the file size and performance of the movie. Second, users of screen magnifiers may find the off stage content conflicts with the on stage visual content they are working with. Screen magnifiers not only increase the size of elements on the stage, but move them to the center. If the on-stage content is inaccessible, off stage content will draw the focus of the screen magnifier creating a very confusing experience visually. This method is often used in conjunction with screen reader detection, but it is important to consider that users may have both a screen reader and magnifier in use simultaneously.
Screen reader detection
Since this case is intended to benefit screen reader users alone, this method is frequently used in conjunction with screen reader detection. Flash has a unique advantage over JavaScript in that it is able to use MSAA to detect the presence of a screen reader. The method Accessibility.isActive() will return a value of true if a screen reader is present and it is currently focused on the Flash content. It is important that this method not be called in the first second or so in the life of the movie, or it could return a false negative. Rather than calling this method in the first frame of a movie, many designers will attach this method to the first button in the movie.
Building off stage content
If Accessibility.isActive() returns a value of true, the contents on screen are set to be inaccessible. Perhaps the easiest means of accomplishing this is to place all of the on stage content in a single movie clip and then set the .silent property of that movie clip to true. It is preferable to use .silent as opposed to altering the visibility of the movie clip since people relying on screen readers might be working together with a sighted person relying on the on stage content visually.
Next, the off stage content is loaded into a single column. This column need not match the height of the movie. It is important that as changes are made on stage that the off stage content is updated at the same time.
Filed under: Graphics 1 & 2
Best Practices for Accessible Flash Design: Part 2
By Bob Regan
Controlling reading order using off stage content
In cases where the application relies on a highly dynamic content, it can be difficult to specify the reading order in advance. In this very small set of applications, it is possible to control the reading order by placing a second set of content off stage in a single column. The on stage content is all rendered as inaccessible to prevent the screen reader from reading it. The second set of content is positioned in a column so the reading order does not jump between unrelated elements.
There are two primary drawbacks to this method. First, it increases the number of objects in the movie, impacting the file size and performance of the movie. Second, users of screen magnifiers may find the off stage content conflicts with the on stage visual content they are working with. Screen magnifiers not only increase the size of elements on the stage, but move them to the center. If the on-stage content is inaccessible, off stage content will draw the focus of the screen magnifier creating a very confusing experience visually. This method is often used in conjunction with screen reader detection, but it is important to consider that users may have both a screen reader and magnifier in use simultaneously.
Screen reader detection
Since this case is intended to benefit screen reader users alone, this method is frequently used in conjunction with screen reader detection. Flash has a unique advantage over JavaScript in that it is able to use MSAA to detect the presence of a screen reader. The method Accessibility.isActive() will return a value of true if a screen reader is present and it is currently focused on the Flash content. It is important that this method not be called in the first second or so in the life of the movie, or it could return a false negative. Rather than calling this method in the first frame of a movie, many designers will attach this method to the first button in the movie.
Building off stage content
If Accessibility.isActive() returns a value of true, the contents on screen are set to be inaccessible. Perhaps the easiest means of accomplishing this is to place all of the on stage content in a single movie clip and then set the .silent property of that movie clip to true. It is preferable to use .silent as opposed to altering the visibility of the movie clip since people relying on screen readers might be working together with a sighted person relying on the on stage content visually.
Next, the off stage content is loaded into a single column. This column need not match the height of the movie. It is important that as changes are made on stage that the off stage content is updated at the same time.
