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The action of adjusting the lens so that the subject appears sharp on the film or CCD. Most cameras now have automatic focus (AF), some have manual focus override (MF) and some have a fixed focus (F) lens that ensures things from about 1.5 meters to infinity are relatively sharp. A few cameras have a power focus (PF), which is a manual method but using a motorised focusing ring. Buying advice: Autofocus is essential if you want to use the camera effortlessly, but occasionally the system is fooled, so make sure the camera has a focus lock or infinity setting or, better still, full manual control. Also check what the closest range is. Some only go down to about one meter which is useless if you want to fill the frame with a small object such as a flower or piece of jewellery.
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Many SLRs and medium-format cameras have interchangeable focusing screens. The benefit is that you can swap the standard split screen for a different pattern to suit the type of photography you are doing. The most common is a grid screen that has a grid of thin lines used to align horizontal and vertical points in the scene. This is a popular choice for architectural photographers and for copying. A plain screen is used for microscope and telescope work, and some prefer a fresnel for focusing with long telephoto lenses where the split screen version may black out.
A method of focusing using a wide aperture to ensure shallow depth of field and put emphasis on an individual area of a scene.
Indicates the number of positions a lens stops at when focused. In theory, lenses with more stops offer a greater stage of focusing zones for sharper results, but in practice this is difficult to see when using a compact camera with more than 30 zones.
Indicates the distance from the film plane to the subject, usually in both feet and meters. Some digital cameras can use lenses originally designed for analogue/film cameras, and in case of digital cameras with cropped sensors the owners should take the crop factor into account when using the focusing scale.
The ring used to adjust the lens so that the subject appears sharp on the film or CCD. Most cameras now have automatic focus (AF), some have manual focus override (MF) and some have a fixed focus (F) lens that ensures things from about 1.5 meters to infinity are relatively sharp. A few cameras have a power focus (PF), which is a manual method, using a motorised focusing ring. Lenses with a ring that allows a good grip make it easier to adjust and focus manually.
Method of focusing the lens, using either a rotating mechanical action or a motorised method, where you enter a distance on the camera. Cameras with mechanical actions often have an aid to help you focus correctly. On some cameras you see the image split in half and as you adjust focus the two halves come together. When the images are lined up the focusing is achieved. Others have an LED indicator that blinks when out of focus and either goes out or stays on when focusing is correct.
A low-cost lens that doesn't have a focusing ring. Found in very basic cameras. The lens is set to a distance of around three meters and relies on the depth of field to bring everything from about one and a half meters to infinity. The quality is always a compromise over a lens with adjustable focusing.
A camera setting that overrides the automatic focusing and sets it to infinity so that landscapes and distant subjects come out sharp regardless of where the camera would automatically have focused. This is an important option to have when shooting though glass as the focusing system can easily be fooled.
A camera focusing system that uses several areas of the screen as focusing points. This ensures better results when the subject is off centre.
A mode to lock the focus to a predetermined point. Useful when the subject is moving fast because you can take the photo as it reaches a certain point or when other influences could affect the focusing such as shooting through glass or in crowded locations.
Sold by filter manufacturers such as Hoya and Cokin to improve the close focusing capability of a lens.
An accessory shoe on a camera that has electrical contacts to trigger and synchronise a flashgun when the camera's shutter fires. More sophisticated cameras have several connection pins for advanced communication between the camera and flash. As well as setting the camera's correct shutter speed, these dedicated pins can also control exposure and focusing modes.
A distant focusing point.
The acceptable limits of things such as focusing, exposure and development.
A focusing mode on many cameras and lenses that allows close up pictures of subjects to be taken with a range of 20cm or less. Digital compact cameras are particularly suited to macro work because they have such short focal lengths. Many models can focus as close as 1cm.
A focusing system that is power controlled by pressing a button or lever on the camera body.
An optical device that’s either built into older cameras or added as an attachment that is used to work out the subject distance by comparing two viewpoints. You see a double image and adjust the lenses until the images form one which gives a distance reading that can then be transferred to the focusing ring.
An SLR or single-lens reflex camera is really designed for the enthusiast or professional photographer, or for the person who can put up with a larger camera in return for increased accuracy and greater versatility. This type of camera has through the lens viewing with a mirror behind the lens and a pentaprism to direct the light passing through the lens to the optical finder. The mirror lifts up out of the way as a photograph is taken. As you look through the lens that takes the picture, the composition can be more accurate. And in most cases you can exchange the lenses, giving you a wider scope of options. The metering and focusing systems are usually more accurate too. Despite all this creativity it's still possible to put most SLRs in a full auto point & shoot mode so anyone could use one with ease, but don't expect to fit one in a pocket! They are much bigger than that. A modern, digital version of the SLR is called a DSLR.
The ability of the cameras lens to focus close to the subject. Most designs allow a close focus of around 20cm. Ones that go closer are often described as having a macro mode.
A metering system that uses several sensors to take readings from various sections around the image and calculates an exposure based on these values. This type of metering, also known as matrix or segment, is better for difficult lighting situations, such as backlit subjects, as it can determine when several sections are brighter than the area that you have focused on and adjust to compensate. Some of the more sophisticated versions couple up to the focusing system to offer even more precise exposure. Basic systems have as few as two metering zones where advanced ones can have eight or more segments.
A type of finder found on old collectable cameras and most medium format models. The finder has a hood to prevent light reducing contrast as you view directly from the focusing screen. It's called a waist level finder because to use it comfortably you'd hold the camera at waist level.
One of two popular methods of camera focusing systems, the other is active. Passive has the advantage over active because it isnt fooled by glass in between the camera and the subject. Its also not dependent on subject distance. It works by measuring the subjects contrast and as such its main downfall is when the subject has no contrast. In such situations, such as snow scene or low light, the lens will focus in and out and may never reach sharp focus. Fortunately many cameras with this system have manual override.
Focusing system in some of the latest autofocus cameras that takes measurements of the subject distance from various parts of the image area, rather than just the centre. Some cameras allow manual selection of this point so you could, for example, set it up to focus on a zone to the left of the image if the subjects you shoot are regularly off centre.
Chromatic aberration, also called "colour fringing" or "purple fringing", is caused by a lens not focusing different wavelengths of light onto the precise same focal plane and/or by a lens rendering a different magnification each of different wavelengths. These two different types of chromatic aberration can both occur in one and the same image. Chromatic aberration can be seen as colour fringing around the boundaries that separate dark and bright parts of the image. It most frequently occurs around the edges of the image, especially in wide angle shots. Despite begin called "colour fringing" or "purple fringing", chromatic aberration can also affect black and white photography. Although a black and white image obviously has no colours in it, chromatic aberration can blur the image.