CCD and CMOS are two ways of turning light into electrical signals in a camera. CCD sensors move charge across the chip and convert it at one output, while CMOS sensors convert it at each pixel. Nearly all current cameras use CMOS, but CCD cameras from earlier years still have devoted fans.
How the Two Designs Work
Both sensors contain a grid of light-sensitive sites that collect charge when photons strike them. In a CCD, the charge is shifted row by row to the edge of the chip and read out through a small number of amplifiers. In a CMOS sensor, each pixel has its own circuitry, so signals can be read directly and in parallel.
Why CMOS Took Over
- CMOS sensors can be made on the same kind of production lines as other chips, which supports mass manufacture.
- They generally use less power, which helps battery life.
- They read out faster, supporting high frame rates, live view and video.
- Extra features such as on-chip processing and autofocus pixels can be built in.
Over time, CMOS image quality improved to match and exceed CCD in most respects, particularly in low light and dynamic range.
The CCD Character
Some photographers describe older CCD cameras as having a distinct colour rendering and a look to the files that they find pleasing. This is subjective and depends on the whole camera design, including lens, colour filters and processing, not just the sensor type. Treat it as a matter of taste rather than a fact about the technology.
Sensor Size Is a Separate Question
CMOS and CCD describe how the chip reads light, not how large it is. A full-frame, APS-C or smaller sensor can be either type. Size affects things such as depth of field, light gathering and the lens you need, while the sensor type affects readout speed, power use and features. Keeping the two ideas apart helps you read camera specifications sensibly.
Side by Side
| Aspect | CMOS | CCD |
|---|---|---|
| Readout | Per pixel or column | Charge shifted to output |
| Power use | Lower | Higher |
| Speed | Fast | Slower |
| Current cameras | Almost universal | Rare, older models |
| Video | Strong | Limited |
Practical Advice
- If you want a modern camera for everyday use, you will be choosing CMOS by default.
- If a CCD camera attracts you for its look, remember it may be limited in low light, speed and battery life.
- Check the age and condition of older cameras, since parts and batteries can be hard to find.
- Judge cameras by sample files that you like, not by sensor labels alone.
FAQ
Do all digital cameras use one of these two?
Almost all do. Some specialised sensors use other designs, but CMOS and CCD cover the vast majority of photography cameras.
Is CCD better in any measurable way?
Older CCDs were known for uniform output and, in global-shutter form, for avoiding certain motion distortions. Modern CMOS designs have largely closed those gaps.
The Short Version
CMOS is the standard today for speed, efficiency and features. CCD is mostly a matter of older cameras and personal taste. Choose a camera by how it fits your needs.
