Understanding CMOS and 3CCD image sensors in cameras

Cameras capture what we see with the help of image sensors; the two most common types being CMOS sensors and CCD sensors. These competing technologies have provided camera manufacturers with two different methods for capturing images for the past decade or so.

What is a CMOS / 3CCD image sensor?

Very simply put, an image sensor is digital circuit that conducts light and converts it into a digital signal. CMOS stands for “complementary metal–oxide–semiconductor” and uses the same tech found in computer processors and RAM, while CCD stands for “charge-coupled device” using a unique technology in widespread use since the 1980’s. The “3” in 3CCD denotes the use of 3 CCD sensors, one for each color (red, green, and blue). CMOS sensors are newer, and have been in use since 1995. CMOS is likely to replace CCD completely.

The reign of CCD sensors has ended; losing popularity

Historically (for the past twenty or so years), CCD sensors have been the standard for mission-critical applications like medicine, astronomy, high-end video production / still photography, and other areas where high-quality is of great concern. However, dramatic improvement in CMOS manufacturing and design (also used for microprocessors and RAM), CMOS based cameras have quickly replaced their CCD based counterparts. Some market insights indicate CMOS dominates well over 90% of the digital imaging market, with scientific CMOS sensors becoming more widely available for sensitive applications.

CMOS sensors are the future

The preferred technology going forward is CMOS, which will eventually leave CCD behind for most applications. Unfortunately, the status quo (and opinion) may not be disrupted until the most recent advancements in CMOS permeate to more mid-grade and mobile cameras. A quick search shows the internet is littered with debates from videographers, movie makers, and seasoned professionals proclaiming superior image quality from CCD / 3CCD compared to CMOS cameras. Don’t be fooled though; these claims don’t hold up.

Ultimately, market demand decides all things. Some proponents of 3CCD cameras argue camera manufacturers are simply trying to “cut costs” and “increase profits” by switching from CCD to CMOS. However, if image quality were truly suffering from this switch, we would see one or several manufacturers rallying against the trend and selling CCD cameras by the truckload. Reasonably enough, consumers prefer CMOS, and so do the manufacturers. The advent of DSLR video cameras is proof that image quality is at an all-time high and CMOS image quality is ever increasing. Even Hollywood has deemed CMOS cameras acceptable, with a variety of block buster movies being made using CMOS based cameras. When compared to CMOS, there is less demand for CCD sensor cameras.

Why are CMOS sensors better than CCD sensors?

CCD sensors are an older, more mature technology that has less potential for further improvement in comparison to CMOS. Even though CCD sensors are well established and easy to manufacture, they do not enjoy the same benefits as their eventual successor. Namely, CMOS sensors share the same fabrication process as computer processors and memory, which means CMOS sensors can partake in fantastic economies of scale. This in laymen’s terms means that many semi-conductor plants are able to produce CMOS sensors with little effort, ultimately lowering the production costs associated with imaging sensors.

In turn, the low cost of CMOS sensor production has made high-quality photo and video cameras available to videographers for under $600. The net effect is the proliferation of video and cameras with fantastic quality. Slow moving industries (like video production and video professionals) tend to eagerly resist what’s “new and different” in technology because it threatens business-as-usual; many feel threatened by new competitors entering their market as the barriers to entry are reduced.

The two major complaints about CMOS sensors

CMOS cameras have traditionally had two shortcomings in comparison to 3CCD cameras. These issues have more or less been fixed in higher-end CMOS sensors. Obviously these technical improvements will take some time to propagate to lower-cost devices.

  1. Low light reception: Fixed – CMOS sensors up until 2009-2011 have generally had very poor low-light reception for event photography and event videography, producing very grainy images. However, modern DSLR cameras are better than ever.
  2. Rolling shutter: Fixed – CMOS sensors up until 2012 have been rolling shutter (inferior to global shutter). This caused a jello-like vision warping or wobbling when panning. Vibrations can also create serious distortions in image quality.

Technical reasons why CMOS cameras are better than CCD

If widespread adoption and accessibility aren’t good enough reasons, let’s look at individual factors within image quality that make CMOS a better fit for photo and video cameras.

  • CMOS sensors consume dramatically less power. This results in cameras with a much longer battery life, making them more suitable for mobile devices.
  • CMOS is generally more robust and durable because it’s an integrated design.
  • CMOS supports full 1080 / 60p video without issue.
  • CMOS does not experience vertical smear.
  • CMOS sensors don’t require special fabricated installations.
  • CMOS sensors are smaller, requiring less physical space (compactness).
  • CMOS sensors are faster, allowing fancy features like auto-focus / auto-white balance, face detection, and more on-camera processing features.
  • CMOS sensors are now being developed with global shutter.
  • CMOS sensors are getting significantly better in low-light (DSLR).

Conclusion: CMOS cameras are superior for consumer applications

That’s really all there is to it. The videography and photography markets are in a state of transition from CCD cameras to CMOS largely in part due to economies of scale in CMOS manufacturing. If you’ve wondered why camera makers are all using CMOS over CCD cameras–it’s simply because the end-users prefer them because of cost, size, and convenience. Hopefully this article has helped those wondering what a CMOS camera is or means: it’s just the type of image sensor.

Image quality has not suffered in any way switching from CCD to CMOS, but has more than likely improved because of the increased speed of CMOS sensors. The ability to manufacture CMOS sensors integrated into a system on a chip allows for additional post processing by the cameras, essentially allowing cameras to leverage additional features like face detection and auto-focus.

Industry professionals who advocate 3CCD / CCD cameras are typically afraid of changing technology and fearful of increased competition within their field. CMOS sensors generally lower the barrier to entry in the professional fields of videography and photography.

Questions about CMOS or CCD cameras? Give feedback or ask us below in the comments!