Some technical terms used in photography

Members often hear people using technical terms at camera club, or in chat between other photographers. But what do those techie terms mean? Here is a brief list of some of them:

Aperture

The adjustable opening—or f-stop—of a lens determines how much light
passes through the lens on its way to the surface of the camera’s
imaging sensor. “Faster” lenses have wider apertures, which in turn
allow for faster shutter speeds. The wider the aperture is set, the
shallower the depth of field will be in the resulting image.

Aspect Ratio

Aspect ratio refers to the shape, or format, of the image produced by
a camera.  Many digital cameras offer the option of switching
between 4:3, 3:2, or 16:9.

Bokeh

Pronounced boh-keh, it refers to the out-of-focus areas in a
photograph with limited depth of field, particularly around, but not
limited to, the highlight areas. Bokeh appears as little circles in the
unsharp areas. Depending upon the shape of the opening formed by the
blades of the lens’s aperture, the circles appear either more or less
circular.

Bracketing

Bracketing involves taking multiple images of the same scene, usually
in 1/3, 1/2, or full-stop increments, to create a choice of exposure
options.

Chromatic Aberration

Also known as color fringing, chromatic aberration occurs when the
collective color wavelengths of an image fail to focus on a common
plane. The results of chromatic aberration are most noticeable around
the edges of high-contrast images, especially toward the edges of the
frame. Chromatic aberration is most common on less expensive lenses,
although even the best optics can occasionally display lower levels of
chromatic aberration, under certain conditions.

Color Space

The range of colors that can be reproduced on a computer monitor or
in print. The most commonly used color spaces for digital imaging are
the baseline sRGB and wider-gamut Adobe RGB (1998).

Composition

The arrangement of subject matter, graphic elements, tones, and light
in a scene. There are no set rules, just suggestions; successful
compositions are ones that best express particular feelings about the
subject or scene.

Depth of Field

Literally, the measure of how much of the background and foreground
area before and beyond your subject is in focus. Depth of field can be
increased by stopping the lens down to smaller apertures. Conversely,
opening the lens to a wider aperture can narrow the depth of field.

Diffuser

Any device that diffuses or spreads out or scatters light in some manner, to give soft light.

DSLR

A single lens reflex (SLR) camera that captures digital images. It includes a camera body with interchangeable lenses.

Exposure

Exposure is the phenomenon of light striking the surface of film or a
digital imaging sensor. The exposure is determined by the volume of
light passing through the lens aperture (f/stop) combined with the
duration of the exposure (shutter speed).

Focal Length

The distance from the lens to the film plane or sensor that focuses
light at infinity. The length, expressed in millimeters, is more useful
as an indication of the angle of view of a particular lens. A shorter
focal length lens, such as a 28mm, offers a wider angle of view than a
longer one, such as 100mm.

HDR

High Dynamic Range (HDR) technique used in imaging and photography to
reproduce a greater dynamic range of luminosity than is possible with
standard digital imaging or photographic techniques. The aim is to
present a similar range of luminance to that experienced through the
human visual system. The human eye, through adaptation of the iris and
other methods, adjusts constantly to adapt to a broad range of luminance
present in the environment. The brain continuously interprets this
information so that a viewer can see in a wide range of light
conditions.

Highlights

The brightest parts of a scene that yield texture or image
information.  A spectral highlight is pure light and will print as
“paper” white.

Histogram

A visual representation of the exposure values of a digital image.
Histograms are most commonly illustrated in graph form by displaying the
light values of the image’s shadows, midtones, and highlights as
vertical peaks and valleys along a horizontal plane. When viewing a
histogram, the shadows are represented on the left side of the graph,
highlights on the right side, and midtones in the central portion of the
graph.

ISO

International Organization of Standardization. A number
indicating an image sensor’s (or film’s) sensitivity to light. The
higher the number, the more sensitive and faster the sensor (or film)
is. Although traditional cameras don’t have a specific ISO rating,
digital cameras do as a way to calibrate their sensitivity to light. ISO
is equivalent to the older ASA. Most digital cameras have native
(basic) ISO ratings of about 100, but can be “extended” far beyond this
base rating in order to capture sharp imagery under lower lighting
conditions. When shooting at extended ISO levels, image quality begins
to suffer in terms of sharpness levels, noise, contrast, and added
“graininess.”

JPEG

The standard for image compression in digital imaging devices. JPEG
is a “lossy” compression format, capable of reducing a digital image
file to about 5% of its normal size. The resulting decompression of the
file can cause “blockiness,” “jaggies,” or “pixelization” in certain
digital images. The greater the compression levels, the more of a chance
pixelization or “blockiness” will occur. The greater the pixel count,
the less of a chance pixelization will occur.

Manual Mode

Manual mode allows the photographer to set the exposure instead of
having the camera do it automatically. In manual, you choose the
aperture, shutter speed and ISO, and those choices affect how light or
dark the image is. Semi-manual modes include aperture priority (where
you only choose the aperture), shutter priority (where you only choose
the shutter speed) and programed auto (where you choose a combination of
aperture and shutter speed together instead of setting them
individually). Manual can also refer to manual focus, or focusing
yourself instead of using the autofocus.

Megapixel

A megapixel contains 1,000,000 pixels and is the unit of measure used to describe the size of the sensor in a digital camera.

Metering

A light meter built into the camera helps guide decisions, indicating
if the camera thinks the image is over or under exposed. Metering is
actually based on a middle gray, so having lighter or darker objects in
the image can throw the metering off a little bit. Metering modes
indicate how the meter is reading the light. Matrix metering means the
camera is reading the light from the entire scene. Center-weighted
metering considers only what’s at the center of the frame and spot
metering measures the light based on where your focus point is.

Mirrorless Camera

A mirrorless interchangeable lens camera (MILC) is a digital camera
with an interchangeable lens and uses an image sensor to provide an
image to a rear display and/or an electronic viewfinder (EVF). It is
called mirrorless since it does not have a mirror in the optical path.

Negative Space

The area which surrounds the main subject in your photo (the main
subject is known as the “positive space”). Also known as white space or
empty space.

Noise

A common problem of digital photography, noise is the appearance of
color artifacts in a digital image. Mostly noticeable in the shadow
areas of images captured at higher ISO ratings, the image processors
used in many current digital cameras utilize noise-suppression software
to minimize the appearance of noise artifacts. Heat build-up due to
continuous shooting in hot environments can also cause noise artifacts
within digital images. Noise is considered the digital version of grain
in film negatives.

Orientation

In photography, orientation refers to the way you take and display
your photographs. The vast majority of photographs from DSLR and
point-and-shoot cameras are taken with a ‘landscape’ or horizontal
orientation, where the photograph is longer than it is tall, while the
advent of cell phone cameras and sites like Pinterest have helped bring
attention to the less common ‘portrait’ or vertical orientation, where a
photograph is taller than it is wide. Even the terms that we use to
refer to this orientations – landscape and portrait – imply that some
subjects are better suited to one orientation than another.

RAW Files

Many pro and semi-pro digital cameras include the option for
capturing raw files, which—unlike JPEGs, TIFFs, and other file
formats—contain all of the data captured during the exposure in an
unedited format. When processed, raw files can be adjusted far more
extensively than images captured in other imaging formats, and can be
saved as JPEGs, TIFFs, etc. The original raw file remains unaltered and
can be reprocessed at any time for other purposes.

Reflector

A device that is used to reflect light, generally back towards the
subject. It can be a specialized factory made reflector or as simple as a
piece of white cardboard.

Rule of Thirds

This compositional rule suggests imagining the image has been divided
into three parts both horizontally and vertically. Often the most
interesting compositions result in placing the subject on one of the
intersections of those imaginary lines, instead of in the center of the
photo.

Shutter Speed

The length of time the shutter remains open when the shutter release
is activated, most commonly expressed in fractions or multiples of a
second.

Vignetting

Darkening of the edges of a photographic image due to the inability
of a lens to evenly distribute light to the corners of the frame. While
correctable with filtration using on-camera, center-weighted neutral
density filters, or electronically in Photoshop, vignetting is often
valuable as a creative device to direct the eye back to the center of
the frame.

White Balance

The camera’s ability to correct color cast or tint under different
lighting conditions including daylight, indoor, fluorescent lighting,
and electronic flash. Also known as “WB,” many cameras offer an Auto WB
mode that is usually—but not always—quite accurate.