Digital Sensors

Charged Couple Devices (CCD) versus Complementary Metal Oxide Semiconductor (CMOS)

	CCD sensors, as mentioned above, create high-quality, low-noise images. CMOS sensors, traditionally, are more susceptible to noise.
	Because each pixel on a CMOS sensor has several transistors located next to it, the light sensitivity of a CMOS chip is lower. Many of the photons hitting the chip hit the transistors instead of the photodiode.
	CMOS sensors traditionally consume little power. Implementing a sensor in CMOS yields a low-power sensor. CCDs, on the other hand, use a process that consumes lots of power. CCDs consume as much as 100 times more power than an equivalent CMOS sensor.
	CMOS chips can be fabricated on just about any standard silicon production line, so they tend to be extremely inexpensive compared to CCD sensors.
	CCD sensors have been mass produced for a longer period of time, so they are more mature. They tend to have higher quality pixels, and more of them.

Based on these differences, you can see that CCDs tend to be used in cameras that focus on high-quality images with lots of pixels and excellent light sensitivity. CMOS sensors usually have lower quality, lower resolution and lower sensitivity. However, CMOS cameras are less expensive and have great battery life.

Source: http://electronics.howstuffworks.com/digital-camera3.htm

Some typical resolutions that you find in digital cameras today include:

	256x256 pixels - You find this resolution on very cheap cameras. This resolution is so low that the picture quality is almost always unacceptable. This is 65,000 total pixels.
	640x480 pixels - This is the low end on most "real" cameras. This resolution is great if you plan to e-mail most of your pictures to friends or post them on a Web site. This is 307,000 total pixels.
	1216x912 pixels - If you are planning to print your images, this is a good resolution. This is a "megapixel" image size -- 1,109,000 total pixels.
	1600x1200 pixels - This is "high resolution." Images taken with this resolution can be printed in larger sizes, such as 8x10 inches, with good results. This is almost 2 million total pixels. You can find cameras today with up to 10.2 million pixels.

Source: http://electronics.howstuffworks.com/digital-camera4.htm

Kodak recommends the following as minimum resolutions for different print sizes:

Print Size	Megapixels	Image Resolution
Wallet	0.3	640x480 pixels
4x5 inches	0.4	768x512 pixels
5x7 inches	0.8	1152x768 pixels
8x10 inches	1.6	1536x1024 pixels

Mr. RC-CAM provides additional comment as it pertains to aerial photography:

	The CMOS cameras have a low cost lens system {plastic}, which often manifests into uneven focus across the entire photo frame. This can be very frustrating to someone that has a photography background. Although there are exceptions, consumer CCD cameras attempt to offer higher quality photos and often use better {glass} optics. Yes, there are crummy CCD optics out there too. No doubt more will go to plastic as they attempt to drive CCD prices down.
	The CMOS imager has slow pixel acquisition time which can cause jaggies or distortion if excessive movement occurs during a snapshot. The CCD cameras have much faster access times and do not produce jaggies. But severe vibrations will still cause focus issues (but nowhere near that of a CMOS camera).
	The typical CMOS imager's dynamic range is less than that of a typical CCD. This issue causes problems with highly contrasted or highly backlight scenes.
	Colors are generally truer on the CCD imagers. Mr. RC-CAM as per RC Groups thread: http://www.rcgroups.com/forums/showthread.php?s=&postid=1626421#post1626421

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Charged Couple Devices (CCD) versus Complementary Metal Oxide Semiconductor (CMOS)

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Copyright © 2003
Last modified: March 18, 2004