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Digital Photography Terms
On this page you will find quick, to the point explanations for common digital photography terms organized in easy to find alphabetical order.Please check back often as new terms are being added regularly to this page.
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Glossary of Digital Photography Terms
Ambient Light
Ambient light is simply another name for natural light. When shooting with ambient or natural light the photographer is using what light is available without any external light sources such as studio flashes or on camera flash. It can include sunlight or artificial light such as street lights, or normal room lighting.Aperture
Aperture is a term that describes how large the lens opening is. The aperture is similar in function to the Iris in our eye. It is a variable opening in the lens that controls the amount of light that is allowed to impact the image sensor.More on how aperture relates to other camera settings....
Angle of View
Angle of View is also called the Field of View. This is the angle of a scene that will be exposed to light by the lens. It is used to determine what category a particular lens will fall into, such as “wide-angle”, “normal” or “telephoto”. Here is a brief chart of some general guidelines when it comes to lens designation, angle of view and focal length.| Lens Type | Focal Length | Angle of View |
| Ultra Wide Angle | 24mm or less | 85 to 180 degrees |
| Wide Angle | 24-35mm | 84 to 64 degrees |
| Normal | 36-60mm | 40 to 62 degrees |
| Telephoto | Above 60mm | 1 to 30 degrees |
Bokeh
The term bokeh
comes from a Japanese word “boke” which
carries a
meaning of something that is blurry, hazy or fuzzy. In photography the term bokeh is used to describe the character, look or appearance of the out of focus areas in a picture. It is not so much how out of focus the background is…as it is how smoothly the out of focus area is blurred and how good it looks.
For a more detailed explanation of bokeh see this article....
Depth of Field
Depth of Field is a measure of how much of a photo is in focus both in front of and behind the central point you focused on. For example a large depth of field would mean that there is a larger area of the photo in focus from the main subject or focal point. This is typically seen in landscape photos where both the foreground objects and the background are in focus and acceptably sharp. A small depth of field means that the distance of an object being in or out of focus can be inches or less depending on the camera and lens. A smaller depth of field is normally seen in portraits and macro photography. It helps isolate the subject from the background and results in that nice blurred background popular in those types of pictures. There are several things that can affect the depth of field. Among those the F-stop or aperture of the lens, the distance the subject is from the camera, the focal length of the lens and the type of camera being used.For a better understanding of how aperture, focal length and image sensor size affect the depth of field check out this cool interactive depth of field calculator.
Watch a video explaining depth of field....
Exposure
Exposure is the term that is used to describe the total amount of light that is able to be captured by the digital camera's image sensor. Exposure is the total amount of light that is allowed to fall on the image sensor during the process of taking a photograph.The correct or ideal exposure for any given situation would be the one that allows the cameras image sensor to capture the digital image with the highest quality while achieving the effect the photographer intended.
Understanding Exposure....
Exposure Compensation
The exposure compensation feature on a camera allows you to quickly adjust the camera exposure to compensate for pictures that are slightly over or under exposed. By pressing the exposure compensation button on your camera (normally unidentified a +/- symbol) you can use the cameras dial to manually adjust the exposure in 1/3 increments up to 2 stops. This feature is extremely valuable and allows you to quickly darken or lighten an image to compensation for different lighting conditions that might otherwise "fool" the camera's built in light meter. It comes in very handy when taking photos of subjects that are back lit or of sunrise or sunset photos.Exposure compensation and your camera histogram go hand in hand. For more on understanding histograms...
Focal Length
Is the distance from the surface of a lens to its focal point. It is normally measured in terms of millimeters “mm” and determines how much magnification the lens provides. A lens with a shorter focal length will have a wider angle of view while a longer focal length will give a narrower angle of view and more magnification.When comparing focal length of different lenses or cameras it is important to realize that the size of the image sensor also plays a role in the overall angle of view or focal equivalent a lens has.
Digital cameras will often refer to their lenses in terms of being “equivalent” to a 35mm film camera lenses. This helps serve as a more uniform measurement of the overall zoom capabilities of the lens or camera and is determined by the actual focal length of the lens and the “focal length multiplier” or “crop factor” associated with the size of the image sensor.
In order to accurately compare the zoom capability of a camera or DSLR and lens combination it is important to understand this relationship and look at the 35mm equivalent focal length as well as the lens speed.
Understanding crop factor and focal length...
"High Key" Images
"High
Key" images are images where the majority of the tonal range is found
in the mid to upper range or the "highlight" areas of the image. They
generally have suppressed contrast levels with lighter shadow areas.
Overall a "high key" image will be brighter with less contrast than a
normally exposed image. But do not mistake an over exposed image for a
legitimate "high key" image."High Key" images are created that way for visual impact and to convey a mood. Some "high key" images are created by using white or light colored backgrounds, having the subject be dressed in light colors and the careful use of lighting to minimize shadows. Another way of creating a "high key" image is by doing adjustments in Photoshop or some other image editor. A well done "high key" image creates a powerful effect and can really make a portrait or photo really stand out.
For an excellent Photoshop tutorial on creating a "high key" image from a normally exposed photo check out this website. It has some great Photoshop tutorials as well as information on graphic tablets such as those from Wacom, Bamboo or Intuos.
Image Sensor
The image sensor is the part of the digital camera that takes the place of film. It is the device that converts the optical image (picture) into an electric signal. As light comes into contact with the image sensor it "exposes' the image senor allowing the photo to be captured electronically.Image sensors come in many different sizes and two basic types. Some cameras use CCD (charge-coupled device) sensors while others use CMOS (complementary metal-oxide-semiconductor) sensors.
More on the importance of image sensor size...
ISO
SO is a term used to describe the light sensitivity of the digital camera sensor. The term ISO was originally used to describe the light sensitivity of camera film or what was commonly referred to as the "film speed". In today's digital cameras the term is used to control how sensitive the the image sensor is to available light.It is short for: "International Organization for Standardization", which is an organization that defines standards for a wide variety of products and industry.
More on how ISO relates to other camera settings....
Lens Speed
Lens Speed is a measure of how much light a lens allows through to the image sensor. It is related to the maximum aperture diameter and is determined by the lowest F-stop the lens is capable of. A lens with a larger maximum aperture such a 2.8 lens will allow more light into the sensor thus allowing you to use a higher shutter speed. Therefore the larger the aperture the “faster” the lens is. This is why some lenses might be referred to as either “fast” or “slow” depending on its maximum aperture when compared to other lenses of the same or similar focal length.More on how aperture relates to other camera settings....
"Low Key" Image
A "low key" image is one where the majority of the tonal
range is
found in the darker or shadow areas of the image. They have a
large amount of contrast with large areas of the image
being darker tones, often black. This technique is sometimes used to
highlight contour lines or create a dramatic portrait where the subject
is highlighted by illuminating the outline or contour of the shape.
"Low
Key" images are created that way for visual impact and to convey a mood
and should not be confused with under exposed images. "Low Key' images
can be created using darker backgrounds, darker clothing and creative
lighting to create the "highlight outline" of the subject. You can also
create "low key" images by doing adjustments in Photoshop or some other
image editor. A well done "low key" image creates a powerful
effect and can make a portrait or photo really
stand out.Megapixels
The term Megapixel simply means one million pixels with a pixel being a single point or dot that makes up part of the picture or image. In digital photography the amount of Megapixels a camera has is used to describe the image resolution it is able to capture.To determine the number of Megapixels a camera is capable of capturing you multiply the number of pixels the camera's image sensor has both vertically and horizontally. That gives you a number that represents the total pixel count for the camera.
While generally most people associate a higher Megapixel camera with better quality photos there are too many other related factors to make that type of sweeping generalization. There are many other factors than simply the amount of Megapixels a camera has that must be given careful consideration when purchasing a digital camera.
Debunking the Megapixel Myth...
What is a Megapixel?...
Normal Lens
A lens that produces an angle of view or perspective that is similar to that of an average human eye.Lenses with a wider field of view are called wide-angle lenses and those with a narrower field of view are referred to as telephoto lenses.The focal length of a “normal lens” depends on the size of the image sensor.For a 35mm film camera or a “Full Frame” DSLR a 50mm lens is generally considered “normal” because it closely matches the diagonal dimension of the image sensor which is 43mm.
For other image senor sizes, such as a point and shoot camera or APS-C DSLR the chart below will show what the focal length is for a “normal” lens”
| Sensor Size | Sensor Diagonal Measurement | Normal Lens |
| 1/3.6" | 5.0mm | 5mm |
| 1/3.2" | 5.7mm | 5.7mm |
| 1/3" | 6.0mm | 6mm |
| 1/2.7" | 6.7mm | 6.7mm |
| 1/2.5" | 7.2mm | 7mm |
| 1/2" | 8.0mm | 8mm |
| 1/1.8" | 8.9mm | 9mm |
| 1/1.7" | 9.5mm | 9.5mm |
| 2/3" | 11.0mm | 11mm |
| 1" | 16.0mm | 16mm |
| Four Thirds | 21.63mm | 22mm |
| APS-C | 27.3mm | 27mm |
| Full Frame | 43.3mm | 50mm |
Reciprocal Rule
The reciprocal rule is one of the basic rules of photography that everyone should be familiar with. It helps us understand the relationship between the focal length of the lens and the lowest shutter speed we can safely use and still avoid motion blur in the photo due to camera shake.The rule simply states that when hand holding a camera your shutter speed should not be lower than the reciprocal of the effective focal length of your camera lens. While that might sound complicated it really isn't. For example if the effective focal length of your lens is 200mm then your shutter speed should not be lower than 1/200 of a second. So the basic formula looks like this: Shutter Speed = 1/focal length.
Like many "rules of photography" this is more of a general guideline than a hard and fast rule. Many things can affect how slow the shutter speed can be for a particular camera and lens combination. Built in image stabilization will allow a slower shutter speed to be used. Also how steady a person can hold the camera will help determine if a faster or slower shutter speed is needed.
To better understand the reciprocal rule and it's importance in avoiding motion blur...
Shutter Speed
Shutter speed is the amount of time the shutter is open allowing light to impact the image sensor. A slower shutter speed means the sensor is exposed to light for a longer period of time.More on how shutter speed relates to other camera settings....
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