Shedding a little light on Camera Sensors

When camera shopping you might notice the acronym CCD or CMOS featured somewhat prominently on advertisements or on the camera itself.
In every digital camera there is a sensor that collects the light projected by the lens and converts it to an analog signal for recording. There are two different imagers that perform this task. CCD (charge-coupled device) and CMOS (complimentary metal-oxide semiconductor) both do the same thing but they do it in different ways with varying strengths and weaknesses. They both contain a grid of 300,000 to 500,000 light sensitive diodes that convert the light into electrical charges (electrons) that are then converted into digital data for storage on a tape, hard drive or DVD.

CCD
When a CCD array is exposed to light, the collectors (capacitors) convert the light into electrons based on how much light and the level of each color of light. Then a controller tells the collectors to transfer their electron charge to their neighbors on down the line till the charge reaches a certain corner. In that corner is a circuit (charge amplifier) that converts the charge into an electrical current which is sampled, digitized and stored as image data.

CMOS
On a CMOS each pixel of the projected image is converted separately at the same time instead of being passed down over the chip like the CCD. The circuitry that converts the charge is often located near or next to the collectors reducing the area for light capture.

Great! Now you might have an idea how it works. But so what. How does that affect your purchase? Well, both of these sensors have their strengths and weaknesses because of the way they are manufactured. Here is a list for you to find the best match for your shooting needs.

OVERALL QUALITY & LOW LIGHT
By low-light I do not just mean nighttime. Keep in mind that if you are shooting indoors you’re in a low light situation, even during the day.

+ CCD better in low light because the entire sensor is dedicated to collecting light.
- CMOS video will be noisy because the light capture area is reduced by extra circuitry.

POWER CONSUMPTION
How much longer will your battery power last?
- CCD sensors can consume as much as 100 times more power than a CMOS.
+ CMOS consumes little power so that battery will last much longer.

PRICE
Budget vs quality.
- CCD are expensive to manufacture and will drive up the price of the camera.
+ CMOS are cheap to produce. Cameras containing CMOS sensor are much cheaper.

Size Matters
Sensors come in different sizes. The smaller the sensor the lower the amount of light it can collect resulting in a a lower quality recording.
Most entry level cameras priced from $100 to $500 contain the smaller 1/6″ sensor.
If you want better quality you will want to look for a camera with a 1/3″ sensor usually on cameras $400 and above.

Three sensors?
Higher quality cameras will have three sensors. A splitter separates the light and projects the red light onto one sensor, green onto the second, and blue onto the last. Each of the colors are collected separately then combined. This results in a much higher quality recording while using three times the power.

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