Glossary

Confused by camera terminology?  Don't know the different between a hot bath and a hot shoe?  You've come to the right place!

Aperture 

The relative size of the opening of a lens.  Expressed in f-stops (f/5.6, f/1.4, etc).  A smaller number (e.g. f/2.8) means more light than a larger number like f/5.6.  See the aperture tutorial by clicking --> here.  Aperture is not affected by the type of camera the lens is attached to.  

Blown, Blow out, Blown (highlights)

A photograph having "blown" highlights generally refers to portions of the image that are so white as to lose any distinguishable details.  Generally to be avoided, it does have its placed in several types of photographs, especially High Key.

Bokeh

The quality of the blur in an image.  Pleasing bokeh is commonly called "creamy" or "smooth", whereas unpleasing bokeh is sometimes called "nervous" or "busy".  

Also sometimes used to indicate the image's DOF - an image with a shallow DOF might be termed to have "lots of bokeh".

Bracketing

The process of taking more than one photo at different settings in order to either combine them using software or obtain a "more correct" photo to choose from later.

Several types of bracketing include exposure bracketing (capturing a "normal" exposure and lighter and/or darker exposures), white balance bracketing (capturing several variants of white balance for an image) and focus bracketing (useful in macro photography - capturing several images with slight shifts in the point of focus, usually to be combined later in software).

Clipping 

"Clipping" in an image is basically 'cutting off' or 'throwing away' some of the bright or dark pixel values in an image, making them purely black or purely white.  Clipping can be seen on a histogram whenever a part of the graph extends beyond the left or right side of the histogram borders.

Clipping isn't necessarily a bad thing - it can be an artistic choice as much as a technical limitation.

Contrast 

How "far apart" the dark values in an image are from the light values.  A high-contrast image will have deep, dark blacks and bright, white highlights.  A low-contrast image will look more subtle and sometimes have a "washed out" appearance.

Crop 

To "cut into" an image to get rid of portions you do not wish to see.  Also used to "zoom into" an image, especially high-resolution images, by filling the screen with only the portion of the image the photographer wishes to display.

Also used as shorthand for "crop camera/sensor", e.g. "I shoot with a crop." 

Crop Camera/Sensor

Typically, any camera having a sensor smaller than that of a full-frame camera.

Crop Factor

The multiplier used to convert the angle of view of a lens, relative to what a full-frame camera would produce.

For instance, putting a 300mm lens on a full-frame camera would produce a standard field of view of 300mm.  Placing this same lens on a crop camera, though, would produce a "zoomed in" image, equivalent to what putting a 450mm lens on a full-frame camera would produce.

Different sensor sizes have different crop factors.

Crushing (Blacks)

Term used to describe the severe clipping of the dark values of an image; essentially, the opposite of Blown Highlights.

Depth of Field (DOF)

How much of an image appears to be in focus.  A shallow DOF means only a thin "slice" of the image is in focus.  A deep/wide DOF means most or all of the image is in focus.  

DOF can be altered four ways: by how far the subject is from the camera, the size of sensor used in the camera, the aperture of the lens during exposure and the focal length of the lens.

Distortion

Any geometric abnormality of an image.  There are several types of distortion, the most common being "barrel" (the object seems to bow outward toward the viewer) and "pincushion" (the object/image seems to bow inward away from the viewer).

Exposure

Generally speaking, how dark or light an image is.  Overexposure means the photo has turned out too bright.  Underexposure means the photo is too dark.

Also used as a noun - "a long exposure" would mean a shot that took a long opening of the shutter in order to create. 

Fill Flash

Using just enough flash on your subject to "fill in" shadows, resulting in a more pleasing (and less contrasty/dark) look.

Focal Length

How long of a "view" the lens gives, expressed in millimeters (mm).  Focal lengths are absolute, technically speaking (a 300mm lens is a 300mm lens is a 300mm lens).  However, due to the arrival of smaller-than-full-frame sensors, sometimes their crop factor is used when talking of the "focal length".  For instance, placing a 300mm lens on a sensor with a 1.5x crop factor may lead someone to say they were shooting with a "450mm equivalent."

There are tons of arguments about this very subject, whether one should say a 300mm lens gives you "reach" when placed on a crop camera vs a full-frame, or not.  Most of the time, this "reach" is coined "pixels-per-duck", relaying the fact that in the digital world, placing a greater density of pixels in a given area means one can essentially "reach" farther with the higher-density sensors.  Since crop cameras generally (but not always) have a higher density of pixels than full-frame cameras, they are usually thought to give you "more reach" with the same lenses.

 Full Frame

Class of camera using an image sensor about the same size as an exposure of 35mm film.  Generally more expensive and fuller-featured than smaller cameras.  Examples of full frame cameras are the Nikon D700/D800 and D3/D4 cameras, Canon 5D, 5D mark II, 1Ds3 cameras, Sony A850 and A900.

HDR (High Dynamic Range)

A method of attempting to fit all the tonal data from a scene into a single photograph.  Camera sensors only have a limited range of values in which they can store data from the dark pixels of an image to the light pixels (their Dynamic Range).

A camera with a very small dynamic range will lose details quicker in both very dark and very bright pixels (see clipping and blown highlights).  

Even the most expensive cameras in the world will encounter photo situations where the darkest part of the image and the brightest part are far apart that it cannot  possibly capture all the data in a single photo.

By using various software or camera techniques, photographers are able to combine two or more images together to capture the range of tonal values in a photograph. 

 High Key

A type of photograph or photographic technique in which most of the image is intentionally "blown out", or made to look extremely bright.  This often has a flattering effect when done in portraits, as it tends to reduce skin detail.  Also often used in my other types of photography when a "clean" or "pure" feeling is being conveyed.  The opposite of a High Key photograph would be Low Key.

Histogram 

A graphical representation of the distribution of pixels from pure black (0) to pure white (255).  The left side of a histogram represents dark values, the right side represents light values.  Very useful to check for image clipping or general exposure properties.

Some cameras allow a histogram to be viewed in three separate parts (red, green, blue) to check for clipping of specific color channels (red typically clips the fastest on digital cameras). 

ISO

The sensitivity of the sensor - carried over from the days of ISO ratings on film.  Typically expressed in whole-hundreds (though intermediate values are possible), like ISO 100, ISO 800, etc.  A higher ISO results in brighter images and/or faster shutter speeds, but also more noise in an image.

Noise

The "static" or "sprinkles" seen in images.  Noise can be caused by several variables, but the most common is a high ISO setting on a camera.  

Luminance Noise - The darker or lighter pixels of an image which contribute a grainy appearance.  Generally speaking, luminance noise is much less objectionable than chroma noise. 

Chroma Noise - The mult-colored speckles in an image.  Chroma noise is usually extremely objectionable (aka - it's ugly!).  Fortunately, it is easily removed in software. 

Metering

Process by which the camera judges how bright or dark the photo is going to be and then adjusts the camera's settings to photograph the "correct" exposure.

RAW

The native data file a camera is able to create.  Raw (or RAW) files contain much more information in a photograph than a JPEG created by the same camera.  Typically, manufacturers use proprietary formats for their RAW files, though notably Pentax is capable of creating .DNG RAW files (created and supported by Adobe and many software programs)

Advantages of RAW include vastly greater image data (very useful for Post Processing), sometimes higher sharpness or less noise.  Disadvantages include larger file formats and the requirements to process the RAW into a viewable format for others to see (unless they also use software able to translate RAW files)

Resolution

A measurement of a camera's sensor output, in millions of pixels, or the measurements of the width and height of a single image.

For cameras, the resolution often refers to the maximum image size it is capable of producing.  For instance, a camera outputting a maximum sized of 6000 x 4000 image would be a 24MP camera.

For images, the resolution is usually just referred to in absolute terms, i.e. 800x600.

As a bit of a factoid, a typical 1920 x 1200 computer monitor (or 1080P HDTV) only has a resolution of about 2MP - Even Apple's and Dell's large 27-inch monitors "only" have a 3MP resolution.  

Sharpness 

On the most basic terms, how "clear" an image is.  A sharp image will show more details and smaller details than a soft image.

Shutter Speed 

How "fast" the camera takes the photo (how long it leaves the shutter open).  Typical cameras can utilize shutter speeds anywhere from 30 seconds (extremely long) to 1/8000th of a second (extremely fast).  

Soft/Softness 

Relating to images - How much an image is "soft", or unsharp.

Relating to lenses - How capable the lens is in creating a sharp image (or not).

Relating to light - The quality of light that produces diffused, pleasing shadows. 

White Balance

The "color" of the light, as determined either automatically by the camera, manually by the photographer, or by the photographer using in-camera presets or settings.

Improper white balance can cause severe color casts on images, depending on how different the in-camera white balance setting is to the actual color of the light in the photograph.  White balance is very difficult to correct in JPG files, yet can be easily changed in RAW photos.