21 Sep 08 Digital Camera Buying Guide
Author: Monty Alexander
Planning to buy a digital camera? Not sure how to get started?
Read on to discover how…..
What do you need the camera for?
If you buy a simple one that can be used at home, you will not get interesting capabilities that you need for taking really good photographic pictures. On the other hand, it would be a waste of your money if you have the latest digital camera only to be used for personal photos at home.
Based on the purpose one can choose from the following main three types.
· Point and shoot: - reasonably compact, with features and size like 35mm cameras.
· Lifestyle: - with moderate features, it’s sleek and compact, so you can carry it around with ease.
· Professional: - with interchangeable lenses, flashes and other accessories, this camera is robust and feature laden, just the right choice for a professional or serious photographer.
These are the important features to look for?
Digital images are made up of dots called pixels. The higher the number of pixels in your image, the better will be the quality of the image. This will therefore enable you to enlarge your image to higher pixel dimensions without creating a pixilated (broken) image.
Compression
Compression shrinks a photo’s file size, thus accommodating more images in the memory card. However compression causes a small amount of data loss. If you need the absolute best-quality images, you have to consider buying a camera that takes uncompressed photos but will accommodate less number of images.
A camera’s memory size will decide the number of images that can be stored. Memory of 128MB will be good enough if you want to use the camera mostly at a social do or a party. If you are on a vacation or when you cannot download images for days at a stretch, a memory of 512MB to 1GB will be most favorable.
Most digital cameras come with at least an optical viewfinder but many digital cameras also come with an LCD screen built into the back. For a digital camera, they vary from 1.5-2.5 inches.
Lens
It is the length of a camera’s lens that determines how much of a scene will fit in a picture. A “Normal” lens is about 50mm, most closely approximate to what your eye sees.
Optical zoom
This enables the photographer to zoom in on an object without any problem in picture quality. Depending on the magnification number, you can zoom in more.
Digital zoom
This feature enables the photographer to zoom in on the centre of the picture by removing the edges of the image.
Focus an exposure
In most cameras, the correct exposure for the lighting conditions is automatically determined. A camera rated ISO 100, has approximately the same light sensitivity as that of a traditional film camera loaded with ISO 100 film. A higher ISO rating means that the camera is more sensitive to light and is potential enough to take pictures in darker settings.
Audio and Movie capture
This feature allows you to record sounds and moving images at the same time, in exactly the same way that a camcorder functions. Some digital cameras provide the facility to record a few seconds of audio with each shot, thus letting you add a personal sound bite to your photos.
Movie mode
This is a feature that lets you take short film clips with your camera. The total record length is typically limited to 10 to 90 seconds.
Most digital cameras come with an in-built flash. Some cameras however include additional features, such as red-eye reduction or night portrait mode.
Image erase
Most cameras also let you select pictures to erase. This handy feature gives you the chance to edit out the photos you don’t want in order to create space in the memory.
Self-timer
A self-timer allows your digital camera for a delayed exposure, usually giving you about 10 seconds before the picture is taken.
Computer connections
Most high-end cameras have software and connections for both Mac and PC computers. However it is necessary to make sure the digital camera you want is compatible with your platform before you buy it.
This feature enables the photographer to capture still images of something moving very fast.
Printing
Nowadays you can buy special printers, depending on the compatibility of your camera, to print off your pictures without connecting it to a PC. This applies both for digital and SLR Professional cameras.
How important is size and portability to you?
Size is another very important factor to consider. If you are to use the camera for non professional purposes the size has to be small as you cannot afford to carry huge sized cameras when you are enjoying a trip.
What is your budget?
Based on the budget the features will vary and the overall offering of a camera. Today’s digital cameras run anywhere from Rs 800 to Rs 30,000, depending on resolution and features. While the initial expense of a digital camera is still high you may find that the added convenience and savings in film and processing costs are worth it.
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19 Sep 08 Digital Camera Basics-resolution, Exposure, Focus, and Storage
Author: Brian Lee
The amount of detail that a camera can capture is called the resolution, and it is measured in pixels. The more pixels a camera has, the more detail it can capture and the larger pictures can be without becoming blurry or “grainy.” High-end consumer cameras can capture over 12 million pixels. Some professional cameras support over 16 million pixels (megapixels), or 20 million pixels for large-format cameras. For comparison, it has been estimated that the quality of 35mm film is about 20 million pixels.
Exposure and Focus
Just as with film, a digital camera has to control the amount of light that reaches the sensor. The two components it uses to do this, the aperture and shutter speed, are also present on conventional cameras.
Aperture: The size of the opening in the camera. The aperture is automatic in most digital cameras, but some allow manual adjustment to give professionals and hobbyists more control over the final image.
Shutter speed: The amount of time that light can pass through the aperture. Unlike film, the light sensor in a digital camera can be reset electronically, so digital cameras have a digital shutter rather than a mechanical shutter.
These two aspects work together to capture the amount of light needed to make a good image. In photographic terms, they set the exposure of the sensor.
In addition to controlling the amount of light, the camera has to adjust the lenses to control how the light is focused on the sensor. In general, the lenses on digital cameras are very similar to conventional camera lenses — some digital cameras can even use conventional lenses. Most use automatic focusing techniques.
The focal length, however, is one important difference between the lens of a digital camera and the lens of a 35mm camera. The focal length is the distance between the lens and the surface of the sensor. Sensors from different manufacturers vary widely in size, but in general they’re smaller than a piece of 35mm film. In order to project the image onto a smaller sensor, the focal length is shortened by the same proportion.
Focal length also determines the magnification, or zoom, when you look through the camera. In 35mm cameras, a 50mm lens gives a natural view of the subject. Increasing the focal length increases the magnification, and objects appear to get closer. The reverse happens when decreasing the focal length. A zoom lens is any lens that has an adjustable focal length, and digital cameras can have optical or digital zoom — some have both. Some cameras also have macro focusing capability, meaning that the camera can take pictures from very close to the subject.
Digital cameras have one of four types of lenses:
1) Fixed-focus, fixed-zoom lenses - These are the kinds of lenses on disposable and inexpensive film cameras — inexpensive and great for snapshots, but fairly limited.
2) Optical-zoom lenses with automatic focus - Similar to the lens on a video camcorder, these have “wide” and “telephoto” options and automatic focus. The camera may or may not support manual focus. These actually change the focal length of the lens rather than just magnifying the information that hits the sensor.
3) Digital-zoom lenses - With digital zoom, the camera takes pixels from the center of the image sensor and interpolates (alters) them to make a full-sized image. Depending on the resolution of the image and the sensor, this approach may create a grainy or fuzzy image. You can manually do the same thing with image processing software — simply snap a picture, cut out the center and magnify it.
4) Replaceable lens systems - These are similar to the replaceable lenses on a 35mm camera. Some digital cameras can use 35mm camera lenses.
Most digital cameras have an LCD screen so you can view your picture right away. This is one of the great advantages of a digital camera — you get immediate feedback on what you capture. Of course, viewing the image on your camera would lose its charm if that’s all you could do. You want to be able to load the picture into your computer or send it directly to a printer. There are several ways to do this.
Although most of today’s cameras are capable of connecting through serial, parallel, SCSI, USB, or FireWire connections, they usually also use some sort of removable storage device. Digital cameras use a number of storage systems. These are like reusable, digital film, and they use a caddy or card reader to transfer the data to a computer. Many involve fixed or removable flash memory. Digital camera manufacturers often develop their own proprietary flash memory devices, including SmartMedia cards, CompactFlash cards and Memory Sticks. Other removable storage device include floppy disks, hard disks (external, or microdrives), and writeable CD’s and DVD’s.
Regardless of what type of storage they use, all digital cameras need lots of room for pictures. They usually store images in one of two formats — TIFF, which is uncompressed, and JPEG, which is compressed. Most cameras use the JPEG file format for storing pictures, and they sometimes offer quality settings (such as medium or high).
To make the most of their storage space, almost all digital cameras use some sort of additional data compression to make the files smaller. One compression routine takes advantage of patterns that repeat. The image can be reconstructed exactly as it was recorded, reducing the file size no more than 50%, often much less. Another compression routine called irrelevancy eliminates some of the more meaningless data, taking advantage of the fact that digital cameras record more information than the human eye can easily detect.
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