Glossary

Aperture #

Aperture in photography refers to the opening in the lens that controls the amount of light entering the camera. It is represented by an f-number, such as f/2.8 or f/16, and affects the depth of field—the range of sharpness in an image—as well as the brightness of the photograph. The maximum opening of the aperture is usually stated on the front of the lens. Most lenses allow adjusting the aperture through aperture blades.

A lower f-number (larger aperture) allows more light to enter, resulting in a shallower depth of field and a brighter image. A higher f-number (smaller aperture) restricts light, leading to a deeper depth of field and a darker image.

The F-number can be calculated by dividing the focal length of the lens by the measured diameter of the lens aperture.

Bokeh #

Bokeh in photography refers to the aesthetic quality of the out-of-focus areas in an image. It is characterized by smooth, pleasingly blurred backgrounds or foregrounds, created by using a wide aperture and a shallow depth of field.

Bokeh adds visual interest by isolating the subject from the background, enhancing the three-dimensional feel, and creating a sense of depth and separation. The shape and quality of bokeh can vary based on factors like lens construction, aperture shape, and the distance between the subject and the background.

Crop Factor #

Crop factor in a digital camera refers to the ratio between the size of the camera’s image sensor and the size of a traditional 35mm film frame. It affects the effective focal length of lenses, making them longer on cameras with smaller sensors, resulting in a narrower field of view compared to a full-frame camera.

A simple equation to calculate the effective focal length of a lens on a given sensor is simply

Effective Focal Length = Focal Length * Crop Factor

https://en.wikipedia.org/wiki/Crop_factor

Depth of Field #

Depth of field (DoF) in photography refers to the range of distance in a scene that appears sharp and in focus. It is influenced by the aperture setting, the distance between the subject and the camera, and the focal length of the lens.

A shallow depth of field occurs when a small portion of the scene is in focus, creating a blurred background, often known as “bokeh,” while a deep depth of field results in a larger area in focus, with more details throughout the scene.

DX Code #

In film photography, a DX code (also called DX number) is a series of metal contacts on the film canister that automatically informs the camera about the film’s ISO (light sensitivity) rating.

This allows the camera to adjust settings like shutter speed and aperture for proper exposure without manual input from the photographer.

Exposure #

Exposure refers to the overall brightness and tonal range of an image. It is determined by three elements: aperture (controls the amount of light), shutter speed (controls the duration of light exposure), and ISO (controls the sensitivity to light). Adjusting these elements, known as the exposure triangle, allows to achieve the desired balance between brightness, motion, and noise in their photographs.

Field of View #

Field of view (FOV) refers to the extent of the scene that is captured and included in the image. It directly affects the composition and perspective of the photograph. A wider field of view encompasses more of the surroundings, making the image feel expansive and providing context, while a narrower field of view isolates the subject and brings attention to specific details. The field of view is mainly determined by the focal length of the capturing lens. Shorter focal lengths capture a wider field of view while longer focal lengths capture a narrow one.

Focal Length #

Focal length in photography is the measure of the distance between the camera’s lens and the image sensor. It determines the field of view and magnification of the captured image, with shorter focal lengths providing a wider view and longer focal lengths magnifying the subject.

ISO #

ISO refers to the light sensitivity of the image sensor (digital) or film (analog). A higher ISO setting makes the camera more responsive to light, enabling photography in situations with less available light or with faster shutter speeds / stopped down apertures. However, increasing the ISO can introduce noise (digital) or grain (analog) into the image, while lower ISO values are suitable for brighter conditions with ample light.

Film Speed #

The sensitivity (ISO or ASA) of a photographic film is often referred to as ‘film speed’. The film speed stated on the box or roll of film is called a film’s ‘box speed’.

Shutter Speed #

Shutter speed (SS) refers to the length of time the camera’s shutter remains open, allowing light to reach the image sensor (digital) or film (analog). Faster shutter speeds freeze motion and are suitable for capturing fast-moving subjects, while slower shutter speeds create motion blur and are useful for emphasizing movement or capturing long-exposure shots. The choice of shutter speed depends on the desired effect and the amount of light available in the scene.

Shutter Speed is most commonly specified in 1/X of a second. A shutter speed of 1/125 means that the shutter is open for 4 milliseconds.

Shutter Angle (Motion Picture) #

Shutter Angle refers to the extent of time during which a movie camera’s shutter remains open to expose the film or image sensor. It is measured in degrees and determines the duration of each frame’s exposure.

The shutter angle is typically calculated based on the frame rate of the camera. For example, if the camera has a frame rate of 25 frames per second (fps), the shutter angle equivalent to 1/25th of a second shutter speed would be 360 degrees. 180 degrees would translate to 1/50th of a second.

Zoom lens #

A zoom lens is a lens that covers a range of focal lengths in a single piece of equipment, most commonly combining multiple usecases (example: wide angle to tele) in one lens body.

Many zoom lenses do not have a consistent maximum aperture over their entire range of focal lengths. A varying aperture is usually stated like ’18-55mm F2.8-4′, meaning the lens has a maximum aperture of 2.8 on the minimum focal length (18mm) and a maximum aperture of 4 at the end of the range of focal lengths (55mm).