FAQ on Camera

What is CCD and CMOS?
CCD AND CMOS imagers both capture images in a similar way. The way an image sensor works is rather complicated so I will try to give you the simple explanation. A image sensor is made up of hundreds of thousands of tiny pixels. Think of them like little windows. Each pixel responds to the presents or absence of light. This information is digitally converted into a signal. These image signals are processed and erased up to 60 times per second and sent out as the video image that you see on your monitor or TV.

CCD Imaging
CCD stands for charged coupled device. CCD is a type of image -sensing technology.
Because CCD cameras have onboard circuitry that provides automatic focus, white balance and iris control the CCD camera produces a razor sharp high quality image.

In a CCD sensor, every pixel's charge is transferred through a limited number (often one) of output nodes to be converted to voltage, buffered, and sent off-chip as an analog signal. This signal requires several chips on the camera board to produce a video signal resulting in a slightly larger area needed to make up the camera. Because other chips are handling the processing all of each pixel on the imaging chip can be devoted to light capture, and the output's uniformity (a key factor in image quality) is high.

CMOS Imaging
CMOS or MOS stands for Complementary Metal-Oxide Semiconductor.
In a CMOS sensor, each pixel has its own charge-to-voltage conversion, but the sensor also includes digitization circuits, so that the chip outputs digital bits. These other functions being incorporated in the same chip reduce the area available for light capture, and with each pixel doing its own conversion, uniformity is lower resulting in a lower quality image.

What does LUX mean?
The lower the lux rating on a camera the better a camera can see in dark situations. A camera with a 0.5 lux rating requires half the light of a camera with a 1.0 lux rating. CCD cameras will dramatically out perform CMOS cameras in low light situations.

What to look for in a camera
The first thing you need to know about camera systems is about the quality image you expect to get out of the camera your going to buy. There are two factors that affect the quality you will get from any given camera. The first factor is the method used by the camera to capture the image and process it into a useable signal. The two acceptable methods are CCD and CMOS. CCD stand for Charged Coupled Device and CMOS stands for Complementary Metal Oxide Semiconductor. The way these two different types of cameras work are complicated to explain so I won't go into detail about that. What you do need to know is which one gives you the best quality. CCD is the higher quality of the two and cost more to produce. If you own a video Camcorder it's most likely using a CCD image sensor because you expect quality out of a Camcorder. While CMOS cameras are much cheaper to produce they lack acceptable quality. CMOS cameras are often found in children's toys and other products that you wouldn't expect much quality for the price your paying.

The quality of camera systems using CMOS is poor but useable. While you can easily make out general objects like people, furniture and other large objects you will not see much detail. Where as with a CCD camera detail is the norm. It's important that you ASK what type of camera system is being used in any system before purchasing.

The second factor you need to consider is resolution. Resolution is the amount of resolvable detail in a picture. It's usually expressed as lines of resolution. The higher the number of the resolution the more detail your will be able to make out in a picture.