Photography and Camera FAQWhat is it? And what does it do?I'll try to keep this FAQ in alphabetical order. I'll
TRY to keep this FAQ in alphabetical order!
35mm Equivalence - The zoom range of a digital camera's lens is often quoted as equivalent to a 35mm camera, so a typical wide-angle to short telephoto 3x zoom would be 35-105mm.
Aperture - The main image lens has an iris built into it which opens wider in low lighting conditions to let through more light.
Aperture Priority - This exposure mode allows you to set the required aperture of the lens and adjusts the shutter speed for the correct exposure.
Artifact - Most often attributed to JPEG compression, artifacts are unwanted attributes that degrade picture quality, such as jagged edges on straight lines.
Auto-bracketing - The camera is set to take a series of exposures, allowing you to choose the most successful at a later stage.
Backlit - A backlit subject, like somebody with their back to the sun, causes exposure problems since their face is in the shadow. A fill flash is required for a balanced exposure.
Bitmap - This image is made up from a large grid of tiny dots or pixels, each of which has its own required brightness and color.
Blooming - See "Fringing"
Burst Mode - Sometimes called Continuous mode, this enables several shots to be taken in quick succession at a faster rate than Single-frame mode, and is measured in frames per second (fps).
CCD - The heart of the camera is the Charge Couple Device (CCD), a chip that converts light into a digital signal. Its surface is divided up into tiny squares (pixels), each of which records one small segment of an image. The more pixels the CCD has, the more detail it can record. Higher resolutions add to the cost of a digital camera and also increase the amount of data the camera has to store. You will always be limited by the maximum resolution of your CCD. At 640x480, for instance, images larger than a snapshot will be of poor quality.
CMYK - Unlike RGB, printed pictures from an inkjet printer are made up of CMYK - the colors Cyan, Magenta, Yellow and Black. Many newer printers use six colors - and some even use eight - adding photo cyan and photo magenta to the mix. Without these, there are problems with certain shades of blue and green that aren't in the CMYK spectrum.
Compact Flash - This is one of the most popular memory cards available, and allows many photos to be stored and then transferred on interchangeable, removable media. Other popular types of cards include SD, Memory Stick, MMC and MicroDrive.
Compression - Compression comes in two forms. The first preserves accuracy, but doesn't save much space; the other called "lossy" compression (and used in digital cameras) saves space but at the expense of image information. This isn't as bad as it sounds because the eye doesn't actually see 16 million colors a digital camera can record. During lossy compression, the camera scans the image, looking for similar pixels and bands them together. The more compression, the more pixels are approximated to the same color, until they start to form bands (hence the word "banding").
Depth of Field - Depth of field describes the range at which any subject can maintain its sharpness, and is determined by three key factors: the size of the lens opening (aperture), the distance between the camera and the subject, and the focal length of your lens. In certain circumstances, the depth of field becomes greater when the size of the lens aperture decreases, the distance from the lens to the subject increases, or the focal length of the lens decreases.
Digital Zoom - Digital zooms and digital magnification generate less sharp images because the new zoomed image is interpolated, rather than genuinely zoomed.
Electronic Viewfinder - These are typically found on more expensive digital cameras, and are a smaller version of the LCD back panel. Low refresh rates can cause problems when panning to cover moving objects.
Exposure Compensation - An override setting which forces the exposure to be slightly shorter or longer than the camera would set automatically.This allows for a forced under or over exposure of the scene, and can be used in tricky lighting.
Fill Flash - This is a low level flash and is primarily used to fill in the shadows of a backlit scene, or to make a foreground object stand out from the back drop.
Focal Length - The focal length of the lens is the distance from the lens to the sensor when focused on infinity. The greater this number, the more powerful the magnification, and the smaller the angle of view.
Fringing - Light captured by a CCD/CMOS sensor is converted into an electrical charge stored on individual pixels. When the limit each pixel can store is reached, it becomes saturated and leaks some charge onto surrounding pixels. This effect which, visually is similar to overexposure, is called fringing or blooming.
Hue - The hue of a color defines its place on the color spectrum. It's often given as a numerical value in image editing packages for easy adjustment of colors.
Image Stabilization - A system in which the lens will send a corrective signal to the camera's CCD when excessive shake is detected, and in turn helps to reduce image blur in photos. Image Stabilization can either be optical or digital.
Interpolated - Software programs can enlarge image resolution beyond the actual resolution by adding extra pixels through complex mathematical calculations.
JPEG - This is the most popular file format for digital photos. JPEG's allow variable compression on a sliding scale, so you can trade off quality against image size.
LCD - A camera's Liquid Crystal Display is a miniature full color screen for reviewing or composing shots, as well as giving a visual display of menu and exposure settings.
Macro - A macro lens can focus on objects at a very close range, providing a magnification effect.
Manual Metering - This exposure mode allows the photographer to set the camera's shutter speed or lens aperture while still taking advantage of the built-in light meter.
Megapixel - A megapixel is literally a million pixels or dots from which a digital photo is made up. A 4000x3000 pixel photo would be 12 megapixels.
Memory Stick - This is Sony's own proprietary form of removable memory card, and is used by many of Sony's digital cameras.
Metering - Choosing the right exposure setting is critical for optimum quality, and metering is the process by which the camera works out this setting. Several methods are employed on most mid and high end cameras, including Evaluative, Center Weight Average and Spot metering.
Noise - Noise is the visual effect of pixel misinterpretation. It appears like film grain, and can occur on long exposures or with higher ISO settings and JPEG compression.
Optical Zoom - This is the maximum zoom range offered by the lens itself, without any help from the electronics built into the camera. (See Digital Zoom)
ppi - This is the number of pixels per inch. 300 ppi is considered to be the usual resolution for high quality prints. Changing the ppi of an image from 72 ppi (screen resolution) to 300 ppi alters the output size, not the number of total pixels in the image.
RAW - A high quality uncompressed file format sometimes used in more expensive digital cameras.
Resolution - In terms of digital cameras, the maximum resolution is the maximum image size that the camera can capture. This is measured in pixels. In printing, the resolution is a measure of the number of individual dots which the printer can fit into one inch. (see PPi)
RGB - All colors are made up from Red, Green and Blue, so devices which transmit light, like televisions and computer screens, work from these primary colors. For colors used in printing, see CMYK for more information.
Saturation - Also known as color purity, this describes how rich and vivid the tones within an image are. Saturated colors contain high proportions of primary colors, while desaturated colors are weak and washed out.
Scene Modes - Most digital cameras have scene modes such as Portrait, Sport and Landscape. These adjust the exposure for greater depth of field, faster shutter speeds and so on, according to certain preset settings and they can be particularly helpful to beginners.
Shutter Priority - This lets the photographer set the required shutter speed and the camera then adjusts the lens aperture for the correct exposure.
Shutter Speed - This is the time the shutter is open, allowing light to fall on the CCD. For example, when using a larger lens aperture, or in bright conditions, a faster shutter speed will prevent over exposure.
SLR - A Single Lens Reflex camera is one in which the image in the viewfinder is taken through the lens, giving an accurate rendering of the picture to be taken. Only those digital cameras which reflect the image formed in a lens directly into a glass pentaprism type viewfinder and with interchangeable lenses, are known as SLRs.
SmartMedia - A once popular memory card type. They're thin and light, but are more fragile than CF cards, have a lower maximum capacity and have mostly been phased out of use by amateur photographers.
Telephoto Lens - Lenses with long focal lengths which produce a telescopic effect for magnifying distant objects, appearing to bring them nearer.
TIFF - A high quality image file format that usually works without compression, though lossless compression is also possible. It is superior in quality to JPEG, but produces much bigger file sizes.
TTL Metering - A meter built into the camera that determines the exposure for the scene by reading the light that passes through the lens.
TWAIN - Meaning: Toolkit Without An Interesting Name - this is an industry standard program that runs between scanners, printers and applications to ensure universal compatibility.
Unsharp Mask - This filter sharpens up slightly blurred images, making edges stand out much better without interferring too much with areas of low contrast.
USB - Much faster than older serial connections, the Universal Serial Bus is ideal for downloading photos from your camera to your PC. Better still, the USB 2.0 standards is around 40 times faster than USB 1.1 and is pretty much the industry standard today.
White Balance - This refers to a system of color correction that the camera uses to deal with difficult lighting conditions and color casts. This can be done automatically or manually.
Wide Angle Lens - Fits much more of a scene into the captured image, makes objects look further away and provides greater depth of field.
Zoom Lens - A variable focal length lens, most commonly with a 3:1 ratio (for example 35 - 105mm). The angle of view and magnification levels alter as the focal length varies.
I hope this helps explain some things for you!
