Photography Terms and Definitions

 

Before we do anything else, I thought it might be a good idea to define some terms that are used throughout this website.  They will be discussed and defined in more detail as we progress, but I just want to make sure that we have a solid foundation for clear communication.  I have not listed these terms in alphabetical order, but rather in the order of relative importance.  Terms that seem to confuse and intimidate most people are at the top of the list.

 

Aperture – A hole or opening through which light travels.

 

Diaphragm – An adjustable mechanism similar to the iris of the human eye that provides a way of changing the size of the aperture of a camera.

 

f-stops – Standardized aperture settings.  Focal Length (f) / Aperture Diameter.

 

Depth of Field – The amount of the image that is in sharp focus.

 

 

 

ISO (International Standardization Organization ) – A measure of light sensitivity in film and in digital camera sensors. Adjusting ISO has no affect upon the light that enters the camera or that the sensor or film sees.  It merely changes the light sensitivity of the sensor or film.

 

Exposure – The total amount of light that the film or sensor sees.

 

 

In-Camera Exposure Meter – A device built into the camera that measures light reflected from the scene being photographed. Exposure Compensation – A way to fine tune the camera’s exposure meter.

 

EV – Exposure Value – A unit of measurement used by light meters and by the Exposure Compensation function of digital cameras.

 

Proper Exposure – The amount of light necessary to produce a clear and vibrant image.

 

 

Histogram – A graph composed of 256 vertical bars used to evaluate exposure.  The farthest left bar represents BLACK, the farthest right bar represents WHITE, and the rest represent shades of grey in Black & White photography or Tonal Values in Color Photography.  The height of any bar is determined by the percentage of the overall image that has the same shade of grey or Tonal Value.  The bars blend in such a way that the appearance is a smooth graph.

 

 

Shutter – A mechanical device that covers the sensor or film except when they are exposed to light.  Some newer digital cameras have electronic Shutters for faster Shutter Speeds.

 

 

Shutter Speed – The amount of time that the shutter is held open in order to expose the film or sensor to light.

 

 

Sensor – The digital equivalent of film.  An electronic device capable of recording visual data.

 

 

SLR camera – A camera with changeable lenses in which the viewfinder image is identical to the image that the sensor sees.  It must also be based on the 35mm film camera model.  We will talk about this in some detail later in the book with visual aids.

 

 

DSLR – A digital SLR camera.

 

 

Neutral Grey Card – A grey card with 18% reflectance that is used as a color calibration device for digital cameras.  Also referred to as 18% grey card, white balance card, or median grey card.

 

 

Lens – Surprisingly, this can be a point of confusion since it can refer to a single piece of glass or a camera lens assembly that consists of several pieces of glass, as well as the aperture, and electronic and mechanical mechanisms.  In this book, lens will mean the lens assembly unless we are talking about optical principles.  In this case, it is much easier to understand the principles if the lens is imagined as a single piece of glass.

 

 

Focal Length – f – the distance from the mid-plane of focused to infinity.  Focal Length is expressed in millimeters (mm).

 

 

Field of View or View Angle – The angle that is defines the image based on the location of the camera.  It can be measured horizontally, vertically, or diagonally.   If measured diagonally, human vision is about 48 degrees.  Camera lenses range from a few degrees to about 120 degrees diagonally.  The FOV (Field of View) is what is seen through the viewfinder at any moment in time.

 

 

Wide-Angle Lens – A lens that has a view angle that is larger than human vision.  The image in the viewfinder has the appearance of having moved backwards.  Up to about 120 degrees diagonally.

 

 

Telephoto Lens – A lens that has a very narrow view angle.  It compresses distance and acts like a magnifying glass.  Angles can be in the range of 8 degrees diagonally.

 

 

Zoom Lens – A camera lens that can be zoomed in or out to more precisely frame the image.

 

 

Basic Zone Modes – Fully automatic camera modes such as Portrait, Landscape, Sports, etc.

 

Creative Modes – Camera modes that give more control to the photographer.

 

Av Mode – Aperture Value Mode or Aperture Preferred Mode. A popular creative mode in which you set the f-stop (aperture size) and the camera selects a Shutter Speed based on the camera’s exposure meter reading.  Used when Depth of Field is most important.

 

Tv Mode – Time Value Mode or Time Preferred Mode.  Another popular creative mode in which you select the Shutter Speed and the camera selects the Aperture Value (f-stop) based on the camera’s exposure meter reading.  Used when freezing the action or motion blur is desired.

 

Manual Mode – The photographer selects all settings.

 

 

• Judge, Al. Mastering Aperture, Shutter Speed, ISO and Exposure