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Home >> Learning >> e-Book on Photography Table of Contents Photography e-Book - Glossary of Terms This glossary is by no means extensive, so if there is a term not available below, or if you would like to supply a term and definition, please contact me with your suggestions. You'll excuse me for having a bit of fun with some of the terms below, all in good jest :-) 18% Grey – the former standard for a middle tone grey, as espoused by Kodak, apparently on the encouragement of Ansel Adams because 18% grey conformed to his Zone system for B&W photography. However, an 18% reflectance is a not true middle grey with the true middle reflectance actually between 12% and 13%. Most camera meters are apparently calibrated for 18% grey reflectance though. Aperture – the diaphragm that controls the amount of light exposed on the film. This diaphragm is usually situated at the back of the lens and opens and closes depending on what setting has been chosen. A wide-open aperture will have its settings at the maximum amount to allow in the most light whereas a stopped-down aperture will have the opening closed to reduce the amount of light entering into the camera’s film plane. ASA (American Standards Association now known as ANSI or America National Standards Institute) – usually used by longtime photographers who broke into photography when the ASA provided the standards for film speed ratings, now handled by the International Standards Organization (ISO). Color – the hues of light that travel along a certain electromagnetic radiation frequency that our brains interpret as color. Colorimeter – a hardware device that is attached to a monitor and used to measure brightness, contrast and white point to allow the accompanying software to create a custom profile. One of the key steps for a properly color managed digital darkroom. Color Management – a coordinated approach by various hardware and software vendors to establish a standard of communication from one device (scanner or camera) to a viewing device (monitor) to an output device (printer) to ensure consistent colors from A to Z in the digital darkroom process. Requires a color management capable software or OS to enjoy though. Circle of Confusion – What a group of photographers is known as when they get together and hash out Nikon versus Canon. Just playing with you J Circle of Confusion or CoC is the point where an out of focus element in your photo, but still within the acceptable depth of field of the photo, is no longer considered a sharp point. The standard CoC measurement is 0.03 inches for an 8x10 enlargement, but other companies use a more stringent figure of 0.025. This is how large a particular subject point in your photo can be and still be considered a sharp point in an enlargement, any larger and it is no longer seen as being s sharp point, so obviously, the larger you print, the smaller your CoC must be. There are various programs and calculators available online that will provide you with the appropriate CoC. Think of a needle. You look at the needle with your eye and it looks sharp, but what if you had a second needle just outside of your eye’s plane of focus, would it still look sharp? That second needle’s point that is ever so slightly out of focus is now a circle instead of a point to your eye, but as long as the circle remains a set measurement size, your eye will still consider it a sharp point. If you take the second needle farther away from your eye then you pass that set measurement so that the circle is larger. Your eye will no longer see it as a sharp point and this where the circle of confusion starts for that second needle. Daylight Exposure - See Sunny 16 below. Depth of Field (DOF) – the zone of what appears to be in sharp focus from a two-dimensional piece of film or photo print. DOF is controlled by the aperture of the lens and a large aperture such as f2.8 has less DOF than a small aperture such as f16. Those grand landscapes you admire in books and prints are taken with small apertures to maximize the DOF so that everything from the foreground to the distant background appears to be in sharp focus. Portrait photos on the other hand are usually taken with shallow DOF to blur out the background and allow all the attention to fall on the subject. The wider your lens is, the greater the DOF and vice versa, the longer your lens, the less DOF you have to work with. Digital Darkroom – What a person whose brain cells have been largely fried by dank development chemicals moves onto after buying a scanner or digital camera, only to have the few good remaining brain cells fried by the electromagnetic radiation from the computer and monitor. Actually, a computer system setup in a dedicated space that should try and conform to an actual ISO standard of having low ambient light and neutral colors. Or, wherever you have the space to setup your computer to edit some digital files and output them from an inkjet printer for tossing into the family album or scrapbook. A good digital darkroom attempts to provide at least the same kind of editing and flexibility as the old chemical based darkroom. Flash Sync – How quickly a dirty old man can flash you and then move on before your brain has comprehended what just happened, or the fastest shutter speed that a camera or lens will be fully open to allow the entire film plane to be exposed to a flash burst. Selecting a faster shutter speed will result in the flash popping while the shutter curtain is still traveling along the film plane, cutting off the subject view. Most focal plane shutters sync at a maximum speed of 1/250 or slower whereas leaf-shutters typically sync at 1/500; however, there are always exceptions to the rule and as technology advances, so to do the shutter speeds. There are leaf shutters that can sync to 1/1000 of a second and there are focal plane shutters that can sync at 1/300. Then there are digital CCD chips with their own electronic shutters that can sync to 1/500. And finally there are various workarounds to the flash sync speed limitations that utilize flash pulses to allow to allow the film plane to be exposed to flash – note though that this is not true flash syncing due to use of multiple flash pulses instead of one continuous burst. Why is flash sync important, a faster flash sync such as 1/250 or 1/500 allows you to mix flash lighting with ambient lighting outdoors to create a more natural photo, or can allow you to freeze motion more effectively than without flash. Focus Plane – the point that the subject is sharply defined. Although we live in a three-dimensional world, film is a two-dimensional medium with no depth. Within the “apparent” depth of our in focus subject, there will be one optimum focus plane with everything in front of or behind the subject that still appears sharp, as being just a benefit of the Depth of Field available from your choice of aperture setting. Guide Number (GN) – the number used to reference the power of a flash unit and also used to determine what the correct exposure setting should be set to on the camera. GN is not of much use in this day or modern TTL conveniences, but is if you’re into using a manual-only flash. Take your GN and divide by the distance in feet your subject is away from the camera. The resulting number is your aperture. Or divide the GN by the aperture you wish to use and the resulting number is how far away the subject must be from the camera in order to be properly exposed by the flash output. E.g. GN 100 divided by 10 feet equals an aperture setting of 10, or f8.5 since 10 is in between f8 and f11. Or GN 100 divided by f8 equals 12.5 feet the subject should be away from the camera. Hyperfocal Distance – the focusing distance for your lens that will maximize the depth of field for the aperture setting chosen. Hyperfocal distance changes for the focal length of the lens being used and what aperture is set. Calculators and charts are available to provide an easy reference since most of the auto focus lenses offered currently do not offer hyperfocal focusing guides. Incident light – is the light that falls onto your subject (contrasted to reflected light). An incident meter measures this type of light and is a more critical form of measuring light in certain situations. Incident metering is the preferred method for measuring complex scenes or highly dark or reflective subjects that could fool a camera’s built-in reflected meter. ISO (International Standards Organization) – based in Europe that provides standards for a wide variety of matters, but for photographers, the key one for us is for film speed ratings. Photography – from the Greek, photo meaning light and graphos meaning to write – write with light. The act of taking a subject seen through a lens and then exposing a copy of that subject onto a piece of film or digital device and then later recovering that image through a chemical or electronic process, both of which can end up on a piece of paper meant for display. Photographer (amateur) – a nut bar that spends more time and money on a hobby than is otherwise warranted or desired by the significant other. Or a person passionate about creating images that provide some personal meaning to the process. Photographer (professional) – a person earning the bulk of his or her income through photographic work and usually someone who can deal with adversity when thrown at them without warning, but not always the case. Reflected light – is light that reflects off of the subject. The meter found inside your camera measures this type of light to determine an exposure for the film being used. There is some debate as to whether or not these built-in meters are calibrated for 18% grey or 13% grey (or 12%) or if they correspond to some other ANSI standards, as Nikon cameras reputedly are. Rule of Thirds – a compositional guide that suggests placing important subject scenes onto imaginary points in the viewfinder divided up into thirds. See Chapter Sepia Tone – a warm toning process used in B&W photos to mimic the aged look of very old B&W prints. Sepia toning is usually a brownish tint, but can also come out in blue or green tints depending on the lab or darkroom enthusiast doing the processing. It is much easier to do Sepia toning digitally today. Shutter – usually made of metal or cloth, but now being created with hybrids and composites such as carbon fiber, that acts as the gate or door that provides the timing of how long light is exposed to film. Controlling the timing also controls the motion for either a freeze-action shot or motion blur subject that conveys movement. There are two main types of shutters used in cameras and lenses, the focal plane shutter which travels vertically or horizontally and the leaf shutter, which opens and closes in circular fashion. Differences between the two are in maximum, fast shutter speeds and flash sync. Spectrophotometer – a high precision measuring device that is used to calibrate monitors as well as printed targets to create custom profiles used in a color managed digital darkroom. Spyder – a misspelled word for an arachnid, an eight legged creature that is not an insect, or a sporty little Italian convertible made by Fiat. Okay, it’s actually what Pantone ColorVision calls their colorimeter, used to measure various monitor hardware settings. Spyder is now casually used to reference any brand’s colorimeter much like Kleenex is used to reference any brand’s soft tissue. Stop - what you should do when you drive your car and come to a red octagon at an intersection, or incremental settings for your aperture ring and shutter speed dial. Using a manual camera as a reference, the change from one shutter speed to the next one up or down is called "a stop", e.g. using 1/60 as our default, a change downwards to 1/30 is a one-stop difference and a change upwards to 1/125 is also a one stop difference. For an aperture ring using f5.6 as an example, a change down to f4 is a one-stop difference and a change upwards to f8 is a one stop difference. Film speeds work the same way and a stop denotes either a halving or doubling of the value for the shutter speed or ISO film rating. For an aperture, the stop indicates a physical opening of the lens' diaphragm for either a halving or doubling of the opening to control the amount of light exposing the film. Sunny 16, or Daylight Exposure - the rule of thumb that dictates that the correct exposure on a sunny day with minimal clouds will be an aperture of f16 and the reciprocal of your film speed for the shutter speed, e.g. with ISO 100 film loaded in the camera, your correct exposure setting is f16 and 1/100 of a second. Since some cameras do not allow for intermediate shutter steps, the closest full stop shutter speed is appropriate, in this example, it would be 1/125. Tripod - John Holmes' nickname, or a stable and portable three-legged support for your camera and/or lens to provide for maximum sharpness and use of slow shutter speeds. Indispensable for quality photography and something every photographer should have very soon after becoming involved in the hobby. |
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