The ABC of Photography – Haloes


A term used to describe the glow that’s created around the edges of objects when they’ve been over-sharpened in Photoshop or other similar photo-editing software. They are even more prevalent in HDR images.

Sources:  Pixabay, NASA,Wikipedia, Susan Wingfield Lamar High School


The ABC of Photography – Diffuser

The ABC of Photography – Diffuser

Any material that scatters the light as it passes through it, Softening the illumination and making shadows less distinct. Diffusers are commonly used with artificial light sources. On sunny days, clouds act as natural diffusers.

Sources:  Pixabay, NASA,Wikipedia, Susan Wingfield Lamar High School

The ABC of Photography – Diffraction


Scattering of light caused by deflection at the edges of an opaque object. Diffraction causes slight fuzziness in the image when the narrowest apertures are used.

Sources:  Pixabay, NASA,Wikipedia, Susan Wingfield Lamar High School


The ABC of Photography – Depth of field

Depth of field

A measure of how much of a picture is in focus, from the nearest point in the scene to the camera that looks sharp, to the furthermost point that looks sharp. Depth of field is dependent on the aperture used, the distance that the lens is focused at, and the focal length of the lens.

Depth of field preview

Device found on some digital SLRs that enables you to see the viewfinder image at the actual aperture you’ll be using for the exposure. This gives a visual indication as to how much depth of field there is, and which parts of the resulting picture will be sharp or blurred. This is necessary because the viewfinder normally only shows the image as it would appear if the widest aperture available was used.


Depth of field scale

A scale found on some lens barrels that can be used to work out the depth of field for particular apertures, and that can be used for manual focus adjustments to maximize or minimize the depth of field.

Depth program

A program exposure mode in which the aperture and shutter speed is set automatically in order to provide the maximum depth of field while maintaining a shutter speed that’s fast enough for hand-held photography. With some cameras, the different subject distances measured by the multipoint autofocus system is also taken into account, and the focus is adjusted to suit.

Sources:  Pixabay, NASA, Wikipedia, Susan Wingfield Lamar High School


The ABC of Photography – Dedicated flashgun

 Dedicated flashgun

A type of flashgun that’s designed to provide direct one-way or two-way communication with the camera. The amount of dedication varies enormously depending on the flashgun and camera. Increased dedication tends to provide a more accurate flash metering, as well as making the flash system easier to use successfully.

Sources:  Pixabay, NASA,Wikipedia, Susan Wingfield Lamar High School


The ABC of Photography – Decisive moment

Decisive moment

The split-second when all the elements of a photograph simultaneously come together. The decisive moment is associated with Cartier-Bresson, who described photography as “the simultaneous recognition, in a fraction of a second, of the significance of an event as well as of a precise organization of forms which give that event its proper expression.”


The ABC of Photography – J

The ABC of Photography – J



A socket into which a plug is inserted to make a connection, also known as a ‘female’ connector. A jack on a camera is used for connecting an accessory such as headphones or a remote shutter release. A 3.5mm mini-jack is used for connecting an external stereo mic or to connect to old TVs.




A term coined by the artist David Hockney (born 1937) to describe his photo-collage work in the 1980s. Hockney’s joiners combined overlapping prints, made at slightly different times and from multiple viewpoints, to make landscapes and portraits. His most elaborate joiners used hundreds of individual prints to make one collage. Other photographers creating joiners (also called ‘panographs’) have followed Hockney’s method of assembling prints, or have combined digital images on screen using photo-stitching software.


JPEG (Joint Photographic Experts Group)

A file format used for digital images. A variable amount of compression can be used to vary the amount of detail stored and the resulting file size. It’s the standard format used by digital cameras (although raw or TIFF formats may also be options)


The ABC of Photography – I

The ABC of Photography – I

Incident light meter

A hand-held light meter that measures the amount of light falling on a subject.


Stands for internal focusing, and is found on many lenses from many manufacturers. The lens is constructed so that it doesn’t change in length as the lens is focused. It also means that the front element doesn’t rotate, which can help with the use of some lens attachments, such as petal-shaped lens hoods and polarising filters.


Image file format

A standard way of encoding information for storage in a computer file. File formats used in photography include JPEG, TIFF, PSD and GIF, all of which are suitable for particular uses. See the separate entries for those formats for details of how they differ.

Image sensor

An integrated circuit chip that converts an optical image into an electronic signal. In current digital cameras, most are either CCD (charged coupled device) or CMOS

(complementary metal-oxide-semiconductor) sensors.

CMOS sensor

CCD sensor



Optical term to describe objects that are so far away from the lens that light from them reaches the lens as parallel rays. In practice, it’s usually used to mean objects that are on or near the horizon. Represented on lenses by the mathematical symbol, ∞.


Infrared photographs

Images recorded on an image sensor or photographic film that’s only sensitive to infrared (IR) light, beyond the spectrum visible to us. Black-and-white IR landscapes have a ‘dreamlike’ quality’; grass and foliage are recorded as almost white, while blue skies become black. Digital cameras can be converted to only shoot IR images by removing the IR blocker in front of the sensor in the camera body and replacing it with a filter that instead blocks visible light.


The name of a hugely popular series of low-cost, easy-to-use cameras made by Kodak. First sold in 1963, Instamatics used Kodak’s cartridge-based 126 film. In 1972, the company introduced the Pocket Instamatic, which used the smaller 110 film.

Inverse square law

This law particularly relates to the use of studio lights or flash, and says that if an object is twice a particular distance from a point source of light, it will receive a quarter of the illumination. For example, if your subject is two metres away, and you increase it to four metres, the resulting fall-off means you’ll need four times the amount of light to keep the same exposure settings. Alternatively, you’ll have to increase the exposure by two stops.


Another name for the diaphragm, or aperture, of a lens.


The abbreviation used for Image Stabilization – the optical camera shake-reduction system found in a wide range of Canon lenses.



Stands for International Organisation for Standardisation. In photography, it refers to a system for measuring and specifying the sensitivity of digital imaging systems and photographic films. The higher the ISO number, the greater the sensitivity to light.

Cameras have an ISO range, enabling you to choose an ISO setting that suits the situation in which you’re shooting.

Sources:  Pixabay, NASA,Wikipedia, Susan Wingfield Lamar High School



Why You Should Use Your Lens Hood

Why You Should Use Your Lens Hood


“What is this thing that came with your lens?” What they are referring to, is the lens hood, included with most new lenses.


A lens hood’s main purpose is to reduce/block light.

If the lens is a prime lens (fixed focal length, non-zooming), the hood will resemble a tube. Slightly larger at one end than the other.

For zoom lenses the hood will have a curved opening at one end. This curve is cut to the zoom range of the lens and allows for the wider field of view, afforded smaller focal lengths, while still attempting to block most light at a longer focal length.


The hood will help block out light that is coming into the lens and causing flare by striking the outer lens elements, (the glass pieces that make up the entire lens), at a less than optimal angle. This is light that never would have made it to the sensor and isn’t needed. Instead, it causes those discolored spots you might have seen. Shaped like the lens aperture (typically a hexagon or octagon).

While lens flare also occurs from light coming directly into the lens, flare from off-angle light can be prevented.


A lens hood will not help you when the sun (or light source) is actually in your shot. While it can help reduce extra light from reflected objects nearby (windows, white walls, etc.), the effect is minimal.

But in reality, you should use the hood whenever you can.

If you happen to be missing your hood for the day, simply use your hand, a book or any other likely object to block out the flare from the main light source, while making sure you don’t get the shading device into the picture. This won’t block the reflected light, which can minutely soften a photo (not to a point most of us will ever realize, mind you) but it will help take care of the main flare issue.