Section 6 Exploring equipment
Exploring equipment: Digital stills camera
Price guide: £60 upwards depending on overall requirements and accessories.
A digital stills camera stores images digitally rather than recording them on film like a traditional 35mm camera. Once a picture has been taken, it can be downloaded to a computer system and printed, manipulated using a graphics program, or incorporated into other applications such as a word-processed document or a presentation.
The quality of the digital photograph is limited by the amount of memory in the camera, the resolution capability of the camera and by the resolution of the final output device. The quality of digital cameras has improved over the last few years and prices have fallen. Although a traditional film-based camera can still produce a better-quality photograph than a digital camera of the same price, it is now possible to take good-quality photographs with a digital camera. The main advantage of digital cameras is that creating images is both inexpensive and fast because there is no film processing.
When choosing a camera, you should also consider any accessories you might need which are not included with the camera, such as a protective carrying case, battery charger and, of course, rechargeable batteries.
As with conventional film cameras the specification of digital cameras varies according to price. The basic models will have a fixed focal length lens and may only contain a built-in storage facility. Moving up the scale will give you additional features such as special scene modes, multiple metering patterns, manual override on settings, macro/close-up capabilities and zoom lenses. At the top end of the scale are the digital single-lens reflex (SLR) cameras with interchangeable lenses.
A digital camera is a blend of conventional film camera features and modern technology consisting of:
· Lens: for forming the images onto an electronic chip.
· Lens aperture: for controlling the light intensity.
· Shutter: for controlling the exposure time. Most digital cameras use auto-exposure and auto-focus mechanisms, but there may be a slight time delay while the camera focuses meaning that not all digital cameras are suitable for high-speed photography.
· Memory card: used to store the photographs when taken. Memory cards can hold any number of photographs, depending on the capacity of the memory card, the type of camera and the resolution you are using. (See also ‘Image storage and downloading’ below.)
· Optical viewfinder: for composing the photograph.
· LCD display panel: for composing and reviewing photographs. It displays the view through the camera lens itself, which can help in avoiding parallax errors (you do not see the same picture through the viewfinder as the camera sees through the lens, so using the viewfinder can sometimes give you more in the photograph than you originally saw). It can also be used to review the photographs stored in the camera (for example to delete unwanted shots), but this uses a lot of battery power.
· Mode dial: for selecting photograph capture or review mode, and for transferring photographs to the computer. Top-end cameras will also include mode settings for recording short video and audio clips, selecting scene modes, manually overriding settings and accessing other special features.
· Menu buttons: to access and manipulate the camera’s options and settings in conjunction with the LCD panel. Top-end cameras may also have other control buttons in the body of the camera to select features such as flash control, macro (close-up) mode or rapid-shoot mode.
· Zoom control: used to zoom in for a close-up shot or to zoom out for a wide-angle shot. The zoom control is normally marked T for telephoto (zoom in) or W for wide-angle (zoom out).
· Flash: on low- to mid-range cameras the flash is normally automatic. On top-end cameras use of the flash is determined by the user and some cameras will also have a hot shoe to enable the use of additional flash guns.
· Batteries: the majority of cameras use A4 batteries, although some of the top-end models use lithium batteries, which tend to be more expensive. Digital cameras use more battery power than conventional film cameras, so the use of rechargeable batteries is recommended.
· Connection points: used to connect the camera to the computer to download photographs. See ‘Image storage and downloading’ below for more information on downloading photographs from the camera.
· AC adapter: used to power the camera in place of the batteries. The AC adapter is particularly useful if a USB cable is being used to download the photographs to a computer, as this process can be a huge drain on the batteries.
Additional points to consider when purchasing a digital camera include:
· Resolution: this is measured in pixels (small squares of colour). The higher the resolution, the better the quality will be, and the larger the photograph can be printed. The number of pixels recorded is measured in millions of pixels – megapixels – achieved by multiplying the number of horizontal pixels that make up the picture by the number of vertical pixels. Cameras are rated by their pixel capacity: a two-megapixel camera will be adequate for taking snapshots, a three-megapixel camera is better for enlargements and a six-megapixel camera will give you very high-quality photographs. Digital cameras record photographs using a charge coupled device (CCD) chip that contains a collection of microscopic light sensors to record single pixels of colour. The smaller the sensors, the finer the detail the camera can read. Normally the camera’s CCD is rated at a certain resolution, meaning that it can capture images of the given resolution: for example a camera with a CCD rate of 2.1 megapixels will produce an image with a resolution of 1600 x 1200 pixels. Because the photographs are recorded digitally, it is possible to change the resolution setting on the camera to allow more photographs to be stored.
· Zoom range: normally referred to as both an optical and digital zoom range. The optical zoom actually zooms in on the subject, whereas the digital zoom enlarges the central portion of the image rather than zooming in, resulting in a loss of picture quality.
Further information
· Digital Camera resource page [http://www.dcresource.com].
· Digital Photography Review [http://www.dpreview.com] and [http://www.dpreview.com/reviews/compare.asp] for a features-search buying guide.
· Cameras and accessories [http://www.buyxyz.co.uk/camera_centre.asp] and [http://www.buyxyz.co.uk/camera_buy_smart.asp] to help you decide what you want from your camera.
· ShortCourses.com offer short online courses to learn all about using a digital camera [http://www.shortcourses.com/index.htm] and information to help you choose the right camera [http://www.shortcourses.com/choosing/contents.htm]
Image storage and downloading
Digital photos are simply computer files. Digital cameras, like all digital devices, store data in memory (like a computer uses a hard drive). Cameras can use various types of memory, with common types being CompactFlashâ, MultiMedia Card, xD Card, Memory Stick™, or built-in memory. With the exception of built-in memory, these are all small cards, no bigger than the size of a credit card, which store from 4Mb to upwards of 800Mb. Some cameras have fixed amounts of built-in memory for storage only. The main types of media used for storage in cameras are:
· Floppy disk: the standard 1.44Mb floppy disks used in computers. Not used by many digital cameras, but popular with some users due to the fact that they are reusable and they make transfer of photographs to the computer easy.
· CD-R: a 3” CD-Recordable disk with a capacity of 156Mb. Not used by many digital cameras, and not reusable, but one of the cheapest forms of storage available.
· CompactFlash: one of the most commonly used storage devices, there are two types: Type 1 which is available in varying capacities up to 512Mb, and Type 2 which is available in varying capacities up to 1Gb. Type 2 CompactFlash cards are sometimes referred to as a MiniDrive or MicroDrive.
· MultiMedia Card: physically the smallest option, available in varying capacities up to 256Mb.
· xD Card: the most recently developed memory card, available in varying capacities up to 512Mb.
· Memory Stick: developed by Sony and licensed to Lexar Media and SanDisk, available in varying capacities up to 128Mb.
Most digital cameras come with software that allows the computer to communicate with the camera and to download the images using a cable attached to the USB port. USB is very fast (about 1.3Mb per second, making it a popular choice for downloading images from a camera) and you do not need to shut down the computer to connect using a USB connection. Some digital cameras are displayed like a normal drive on the desktop and allow downloads to take place by dragging and dropping images into a new folder.
There are also USB devices that can read directly from memory cards such as the CompactFlash and xD Card. These are commonly known as card readers, and work like a normal disk drive. Photographs are downloaded by removing the memory card from the camera and inserting it into the card reader. With this method you do not have to have the camera software installed on the computer, and you are not running down the batteries while you download your images. You can also delete the image files from the memory card quickly in the same way that you would delete files from a floppy disk.
Further information
· Google DealTime offers a comparison of card readers of various price ranges [http://www.google.dealtime.co.uk/xKW-usb_card_reader/NS-1/linkin_id-3032076/GS.html].
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