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Nov. 2002
The quickest and easiest way to feed live pictures
to your Web site is with any low cost PC-video
cameras sold by companies such as
Intel,
Creative, Kodak
and Logitech. Prices start from $100 (the more
expensive models feature built-in microphones and sharper
resolutions).
Not all Webcams are created equal. In fact, it's
harder to gauge Webcams by the bit depth and resolution than
it is for digital still cameras. Part of the reason for this is that, for
performance reasons, most common Webcam video resolutions are still
relatively small (typically 160 x 120 and 320 x 240 pixels).
This isn't helped by the fact that most Webcams use relatively low quality
lenses and charge coupled devices (CCD). The CCD is a light sensitive
computer chip, which converts light into an electrical charge, the intensity
of which determines the colour of each pixel in the image. Newer cameras may
have a CMOS (complementary metal-oxide semiconductor) computer chip, which
senses light in the same way. These are cheaper to
manufacture -- and hence may lower the price of the camera -- and draw less
power than a CCD. Unfortunately, CMOS cameras rarely achieve the image
quality of CCD cameras. Look for a
camera that adjusts reliably to a variety of light conditions and renders
colours realistically. This can be hard to test at retail stores, which
don't often have up-and-running cameras to play with.
Light levels will play an important part in the quality of your
images, but you should be safe if you can ensure either an abundance of
natural light or a 100-watt light globe around
your camera's viewing area. Another important thing to keep in mind is that
desktop Webcams are point-and-shoot devices, designed to keep things simple
and automatically handle features like white balance. Yet "automatic"
doesn't necessarily mean "best".
Before you buy, check out the camera's controls to see how much the
camera handles automatically and what you can fine-tune yourself. You may be
able to adjust the aperture on your camera to let in more light, or
alter the colour balance (the intensity of reds,
greens and blues) if you find one tone is dominating the picture.
One thing that you can control is the angle of the camera unit, which is set
by the PC mount. A good mount will let you pan (move side-to-side)
and tilt (move up-and-down) the camera lens while remaining steady.
Cameras that sit on a stand are much harder to align and keep in place. Take
note of the resolutions that a camera supports, and especially the frames
per second (fps) for each resolution. You'll probably find little variation
in the range of available resolutions (like 320 x 240, as mentioned above)
but the fps rate can make a big difference to how your Webcam site works,
particularly at higher resolutions.
For inexpensive Webcams, this will generally vary from 15 to 30fps.
Essentially, the higher the fps then the less time your camera needs to take
a picture, and by extension, the sooner it is
ready to take another picture. However, this should not be a major concern
unless you plan to stream live video -- you will neither
benefit nor be hampered by the fps rate if your Webcam simply
takes single shots every minute or so.
Some cameras have a button for taking manual pictures. This isn't an
important feature at all if -- as in the case of Webcams -- you are going to
use software to take pictures automatically. In
fact, even if you want to take single shots manually, it's best to avoid the
set-top button as you may obscure the image or even bump the camera and ruin
your careful positioning.
Finally, check the length of the camera's cable. If you want your Webcam to
monitor a large area, you may prefer a longer cable that lets you move the
camera closer to the likely main area of action, or even mount it overhead.
Once the camera is hooked up to your PC, get to know it. Play with it for a
bit. Change the image sizes and check how the image degrades or improves, or
if there's any noticeable variation in the
picture's refresh rate. Alter the colour properties and see if your
pictures become crisper or clearer. Check if your camera automatically
focuses on objects within its view or maintains a fixed range. Discover all
the fun things you can do with your camera before moving on. |
