Digital Cameras

Digital Camera Overview

In comparison to today’s cameras, the early digital cameras were crude electronic devices with plastic lenses, few features, and inadequate image quality. Cameras using the current digital technology are now on par with traditional film cameras. They are loaded with features, including zoom, flash, exposure controls, special effects, and some even offer video-capture capabilities.  Most tend to have excellent glass lenses and generally offer good to superb image quality. They support a wide variety of resolutions from snapshot prints and images appropriate for the Web to large 16x20 inch prints. The important thing is to choose a camera with a resolution suited to your output purpose.

The good news is there are many cameras to choose from: point-and-shoot or pro models, VGA or multi-megapixel resolution, simple and spartan or loaded-for-bear features. The bad news is that with more than 250 different models on the market, finding the camera that meets your needs may take some time and research.  I hope I can help shed some light on what you should consider before making the jump to digital photo technology

Reality Check

As with any new technology, there are a lot of acronyms, inaccuracies, and falsehoods to weed through. Hopefully, I can dispel some of the misconceptions.

What influences the sales of digital cameras? When you get right down to it, it's all about the numbers, specifically the resolution. Manufacturers are touting higher and higher resolutions-6,7 , 8, 10, 12 megapixels-and many buyers assume that the number of pixels (or points of data) that a camera can capture is the definitive measure of image quality. If it has a higher resolution, it must be better, right?  Wrong.

Resolution is simply the measure of the amount of data (the pixels) saved in the picture file. This relates to how large the image may be printed or displayed--not how well the picture will appear. On the other hand, image quality is the sum of all that the camera does to create the picture.

Defining image quality begins with the camera's optics-how good the lens is. At the very least, the lens should be made of glass and not plastic. A good lens, whether it has a zoom capability or not, provides the best chance for producing a really great photo-one that is sharp, clean, and colorful.

Once the picture is in the camera, it goes through quite a bit of data manipulation, image processing, and color management. Then the picture is organized into a file, compressed, and saved. All these steps have a major influence over the image quality. But because all this happens under the hood, so to speak, the only way to determine the quality of all this computing is by actually using the camera and analyzing the picture.

Of course, resolution does matter when you're shopping for a digital camera. That's because the amount of data that's captured determines what you can do with the picture. The table below provides a quick summary of camera resolutions and the size prints they can produce. Just remember the age-old adage, it's quality not quantity that matters.

Top Ten Buying Tips

1. Select a digital camera with a maximum resolution that meets your largest typical output. If your images will primarily be used on the Web, you'll need a camera that supports a 640-by-480 resolution (VGA). For snapshots check out cameras that support 1,024-by-768 (XGA), and enlargements will require a 3-megapixel camera or better.  Remember, the more megapixels, the more bucks you’ll spend.
2. Make sure the camera has all the features you need, such as video, audio and panorama. This is a technology that you might have to live with for quite some  time.
3. When comparing costs, don't forget to calculate the extras that may or may not be included, such as rechargeable batteries, an AC adapter, and a larger memory card. Many cameras come with built-in 16MB or 32MB memory, but you will probably want to buy plug-in memory cards in the 512MB to 1024MB range to extend your picture storage capability. With the smaller built-in memory, you will spend considerable time uploading photo files so you can take more pictures.  If you’re going to travel, you might want to consider a 2GB MB card.
4. Try to buy a digital camera that has a USB interface. This will simplify the image transfer process. With USB, the computer sees the camera as a disk drive, so all you have to do is drag and drop the images into Windows Explorer. Even better, buy a portable USB flash memory reader that will accept your type of memory cards.  This saves having the batteries drained while transferring photos to your PC. Inexpensive memory card readers can be purchased for less than $20.  If you already have other USB devices attached to your PC, you can free up some cables.
5. When looking at zooms, what counts is how large the optical zoom is--not the digital zoom. Digital zoom is actually a software function that involves cropping and magnifying an image. Expect to get at least a 3x level of optical zoom. Digital zoom will interpolate between the pixels for larger images, but you will lose picture quality and sharpness.  As the digital zoom increases, the image will look blocky.
6. If you don't know an f-stop from a white balance, a digital camera that has lots of modes and settings will be overkill.
7. If you wear eyeglasses, make sure that your digital camera has a focusable diopter in the optical viewfinder, which automatically adjusts the focal length for you.
8. Look for a digital camera that comes with a pocket-size instruction manual instead of one on a CD-ROM.
9. For small or arthritic hands, look for a digital camera with a limited number of buttons, and make sure they are large.
10. Test how fast the camera shoots. There is a built-in recycle time between when you snap the picture and when the camera is ready to take another shot. You will probably be unhappy with any digital camera that takes longer than 5 seconds before allowing you to shoot again.  Some of the older digital cameras can take up to 30 seconds to recycle for a new photo.

The ABCs of Digital Cameras

Aperture - A hole, iris, or opening through which light enters the lens and your camera. The larger the aperture is, the greater the photosensitivity of the system. A smaller aperture, however, will give greater depth of field to a picture. Measured in f-stops (which is the amount of light allowed to pass through the lens to the film), a small aperture has a high number, such as f8 or f11. Conversely, a larger aperture has a smaller number, such as f2.8. To set a camera for proper exposure, the aperture must be balanced against the shutter speed. The faster the shutter speed, the larger the aperture must be, and vice versa, to admit the right amount of light to the image sensor for proper exposure.

Compression - A process that compacts and shrinks an image file size so that the file takes up less space in your camera, memory card, and computer. Compressing and saving an image actually takes less time than saving an uncompressed image. Smaller files are quicker to use for e-mail and on the Web. When a file is over-compressed, image quality can be seriously degraded.

Depth of field - An indication of how much of a scene will be sharp and in focus. A greater depth of field will have a wider range of distance from the subject to the background and foreground with everything in focus. On the other hand, a narrow depth of field will concentrate its area of focus to within a minimum distance surrounding the central subject. For instance, if your subject is standing in a ballpark, using a narrow depth of field will make most of the ballpark, other than the area closest to the subject, look blurry. A greater depth of field would keep most of the ballpark in focus.

Image sensor - The semiconductor chip in your digital camera that replaces film. It captures the light of your scene or subject and turns it into electrical signals that the camera can understand and use. These signals, in turn, are converted within the camera to digital data that your computer can understand and use.

Interpolation - A process that increases the image file size and can occur either in your camera or by computer software. As a rule, interpolation does not improve image quality and can decrease sharpness. It is the opposite of compression.

LCD viewfinder - A small electronic screen on the back of the camera that displays what the lens sees. It's used to compose your picture, choose your settings, and review (play back) your just-shot photos.

Megapixel - A measure of a digital camera's resolution. For instance, one megapixel means that the camera can capture up to 1 million pixels, or points of data.

Memory card - A removable storage device that saves the images your digital camera captures. When it is full, you can swap the memory card for another and continue shooting. A card reader can be attached to your computer for opening and saving image files outside of your camera. The most common types of memory cards are CompactFlash (CF),  SmartMedia (SM), Secure Digital (SD), mini Secure Digital (mini SD), micro Secure Digital (micro SD) and Memory Stick (MS). You must use the right type of card for your digital camera. Memory cards come in various densities, as do any other drive or storage device.

Pixel - A point of data in a digital image, used to measure resolution. It is also the tiny photosensitive area, or photo site, on an image sensor. A digital camera's resolution is a measure of the number of pixels on its image sensor.

Shutter speed - The measure of how long a camera will allow light to enter it. In traditional film cameras, there is a physical, mechanical shutter in the lens that opens and closes to regulate how long the film is exposed to light. Though many digital cameras have both an electronic and a mechanical shutter, inexpensive models rely solely upon electronic shutters that turn off the photosensitivity of the image sensor.

If you’re looking for a good place to buy digital camera equipment, I can recommend the B & H Photo Video web site as an excellent place to shop. They have discounted prices, prompt service and no obnoxious salesman that try to sell you over-priced accessory packages.