Photography Glossary

Aperture

See F-stop.

Aperture Priority

A shooting mode on modern cameras where the aperture is set to a desired value and the camera automatically determines the shutter speed to properly expose the picture.

APS-C

Refers to the size of the optical sensor in digital cameras, or the size of the film’s frame in film cameras. APS-C is approximately 40% smaller than a full frame sensor or 35mm film. (Full size sensors are the same size as 35mm film frames.) What this means, is that with a standard lens on your Digital SLR with an APS-C size sensor you will get 1.6x the focal length of the lens.

Bokeh

Refers to the aesthetic quality of the portions of the image that are out of focus.

Bracketing

A method of taking multiple pictures with different exposures or settings either for High Definition Photography, or when it is difficult to obtain the proper settings with a single shot . Typically your camera will allow you to set three or more values at which the pictures or taken; for example you may bracket based on f-stop, or even shutter speed with some cameras where holding down the shutter button will take a picture at -1 f-stop, 0 f-stops (properly exposed), and +1 f-stop.

CMOS Sensor

The image sensor that has replaced film in modern cameras. The CMOS stands for Complimentary Metal Oxide Semiconductor, and is just one type of sensor modern cameras are using.

Depth of Field

A term used to describe the amount of the depth of an area that is in focus in a picture. In other words, a higher depth of field will give more in focus than a lower one given the same subject and picture. The f-stop and lens focal length are just two things that will impact your depth of field.

DOF

See Depth of Field

DSLR

Digital Single Lens Reflex Camera-See SLR.

EOS

Stands for (Electro-Optical System) and is specific to the Canon line of cameras, the EOS camera system was introduced in 1987, and is still in use today.

Exposure

Exposure is a general term to indicate the brightness of an image. Something with improper exposure generally does not have a good light distribution, and will lose detail in the darker parts of the image. Similarly, over exposing an image may cause you to lose detail in the brighter parts of the image.

Film Speed

See ISO

Focal Length

When referencing lenses, this is the distance it takes for light to converge beyond the lens. Subjects inside of the focal length of a lens will have a more shallow depth of field than those outside of it. With a 35mm camera, if you have a lens with a focal length of 35mm, you will capture images at a ratio 1:1 (no zoom, no wide angle). Focal lengths less than the size of your sensor are considered Wide Angle, and greater are considered zoom lenses.

Focal Ratio

See F-Stop.

F-Stop

Directly correlates to the diameter of the entrance pupil in a lens. The smaller the f-stop, the larger the pupil and more light allowed into the camera as it is expressed in terms of focal length (f/1.4 means focal length divided by 1.4 where 1.4 Is the f-stop). Each increment of an f-stop will reduce the amount of light let in by half! Standard values are: 1.4, 2, 2.8, 4, 5.6, and 8.

Full-Size Frame

Typically accepted as a 35mm sensor or 35mm film.

ISO

Previously referred to as Film Speed, the ISO used to determine the sensitivity of film to light. The higher the ISO, the less time needed to properly develop the film – even if it was at the expense of a grainy or less defined picture. In modern digital cameras where there is no film, changing to a higher ISO value will instruct the camera to properly expose the image in less time, typically resulting in increased image noise.

Macro

A type of photography where the focal distance is extremely small. This typically produces images of subjects at multiple times their original size.

Relative Aperture

See F-Stop.

Shutter Priority

A shooting mode on modern cameras where the shutter speed is set to a desired value and the camera automatically determines the f-stop to properly expose the picture.

Shutter Speed

The speed that the shutter will open and close- giving the exact time that light is allowed to hit the sensor or film. Shutter speeds are typically defined in seconds, so a shutter speed of 1/40 is 1/40th of a second. A faster shutter speed means less light is allowed into the camera.

SLR

Stands for Single Lens Reflex. Historically refers to a type of camera where there is a movable mirror between the lens and sensor or film. This mirror allows the viewfinder to see the image as it appears through the lens. When the picture is taken, the mirror flips up before the shutter opens, and falls back into place once it closes if in standard operating mode.

Vignette

The visual distortion of the areas around an image historically caused by poor lens optics. Recently, it is done digitally or with specially crafted lenses for artistic effect.