by Tom Hirsch
The advantages of digital in a moment, but first a little review. Last time we compared the various degrees of compression in JPEG files. It was noted that JPEG compresses pictures so that more can be stored on a memory card. JPEG images can be compressed to the max if they will only be viewed on the computer monitor or sent as e-mail pictures.
An idea to consider was to shoot everything at the highest JPEG setting, then convert to an appropriate degree of JPEG quality in the computer, but only if the compressed image would be used for viewing on the computer, or for e-mailing. Then you'd have both a high-quality image and a compressed image on the computer.
Understandably, shooting everything at the highest quality could fill up a small-capacity card very quickly. Most digital cameras are shipped with a 16, 32 or 64 megabyte card. Whether this is enough depends on the maximum image capability of the camera and the needs of the photographer. For example, a 16-megabyte card in a 5-megapixel camera might only provide space for 10 images using the best JPEG quality, and 80 at the highest compression ratio. For only e-mailing images, this size card would be adequate because only the lowest quality setting would need to be used. But on a sightseeing trip, you'd want images of the highest quality. What's a photographer to do?
The solution is simple: Buy an additional card. In selecting a supplementary memory card, use the 16X rule that I just made up. Buy a card that has 16 times the maximum rating of the camera. For example, if you have a 1-megapixel camera, buy a 16-megabyte card. A 32-megabyte card would go with a 2-megapixel camera, etc.
If you travel or otherwise do a lot of shooting, you could go beyond this generalization. The rule of 50X might be more appropriate for your needs. Cards come in 8, 16, 32, 64, 128, 192, 256, 512 megabytes and 1 gigabyte (that's one billion bytes). If need be, there are also larger capacity cards. Along with the price of digital cameras, the cost of memory cards is also dropping.
Although the initial price of a digital camera might seem high compared with that of a film camera, the difference is offset when you compare the cost (and capacity) of film with that of a memory card. The price of a 24 exposure roll of film, including processing, is about $10. Five rolls of film, including processing, would cost more than the price of most 64 megabyte cards, and some 128 MB cards. Film can be used only once. Not so with digital memory cards. After the pictures have been taken to a store to be printed, or downloaded onto a computer, the memory card can be erased and used over and over again. This makes for a very practical system. The cost of the digital camera could pay for itself in a very short time, and the more digital pictures you take, the more you'd be saving.
Digital cameras have an LCD (Liquid-Crystal Diode) monitor on the back that lets you review your shots right after they've been taken. You can delete the bad ones on the spot. With film, you must wait until the film is processed before you can view and edit your images.
One of the fun things in digital photography is getting close to the subject. Most digital cameras have a macro mode that lets you get within inches. With the LCD monitor turned on, you'll be able to move in and look right through the lens so you can get a good approximation of what your picture will look like. With some compact film cameras you can do the same thing, but without an LCD monitor, you can never be sure of the composition or framing.
Other advantages of digital photography can be found on individual digital cameras. Some disadvantages of digital will be covered next time.