For a long time, the CCD sensor was the prevalent technology for capturing high-quality, low-noise images. But CCD sensors are expensive to manufacture, so they often come with a higher price tag. They also consume more power than CMOS sensors, sometimes a hundred times more. Luckily, CMOS sensor technology has advanced to the point where it is fast approaching the quality and capabilities of CCD technology, and with a significantly lower price tag, smaller size, and power consumption.

CMOSimage sensor

Beginner photography enthusiasts are often a bit mystified when first learning about depth of field (DOF). How exactly do camera angles and f-stops affect DOF? It isn't always an easy concept to grasp, but mastering it takes your photography to a whole new level.  In this short article, I explain DOF as I did in part of my 'Finding the Perfect Portrait Lens' course on lynda.com. Watch one of the videos (below) or read on for more details.

A CCD sensor is a “charged coupled device.” Just like a CMOS sensor, it converts light into electrons. Unlike a CMOS sensor, it is an analog device. It is a silicon chip that contains an array of photosensitive sites. Being an analog device, output is immediately converted to a digital signal by an analog-to-digital converter. The voltage is read from each site to reconstruct an image.

Canon is leading the way with some of the most exciting CMOS sensor innovations at the pixel level.  Canon’s 2U250MRXS CMOS sensor, for example, features an unprecedented 250 MP resolution capable of capturing detail 125 times greater than in full HD. This APS-H format sensor leverages a square pixel arrangement of 1.5µm x 1.5µm pixels, achieving ultra-high resolution in a compact design for use in a wide range of applications.

Now that you know a bit about what DOF is, the next step is to dig deeper into how you can actually control and create a shallow depth field. Most photographers (even many pros) aren't aware that there are 4 main factors that influence DOF: Sensor Size, Focal Length, Aperture, Distance.

A CMOS sensor is a digital device. CMOS stands for ‘complementary metal-oxide semiconductor.’ A CMOS sensor converts the charge from a photosensitive pixel to a voltage at the pixel site. The signal is then multiplexed by row and column to multiple on-chip, digital-to-analog converters. CMOS sensors have high speed, low sensitivity, and high, fixed-pattern noise.

The way CMOS and CCD sensors respond to infrared wavelengths is also important for machine vision systems. CMOS sensors are more sensitive to IR wavelengths than CCD sensors. CMOS chip and camera manufacturers have used this advantage to capture IR light and provide additional imaging capabilities for image recognition.

Phase 1 Technology Corp., 44 Jefryn Boulevard, Suite Y, Deer Park, New York 11729 Email: [email protected]  |  Telephone: (631) 254-2600

As you can see, I love shooting with a  shallow DOF!!! One of the reasons is because it's replicates how the human eye sees the world. Let me explain. Let's say, that I'm in my back yard and all of a sudden I see my daughter running towards me across the lawn. What happens, is that I focus on her and everything else becomes a blur. And in a sense, that's a lot like having a shallow depth of field. The same thing happens when you are talking with someone you admire or someone you love. Your focus becomes so shallow that all you can see if that person in front of you. So for me, one of the main reasons why I use a shallow depth of field isn't just because it allows me to create a unique look, but because it allows me to add that kind of feeling to my photographs.

Photographers and cinematographers should remember the following: depth-of-field has nothing to do with focal length. It has nothing to do with angle-of-view. It makes no difference if one uses a telephoto lens or a wide-angle lens. Depth-of-field relates only to the following two variables: (1) image size, and (2) aperture opening (F-#). In turn, these two variables relate to a physical effect called the "circle of confusion." The smaller the image in your picture frame, the greater the depth-of-field; the larger the image, the shallower the depth-of-field. The smaller the aperture opening on the lens iris (the higher the F-#), the greater the depth-of-field for any given image size; the wider the aperture opening (the lower the F-#), the shallower the depth-of-field. If you frame a close-up with a narrow-angle lens (i.e., "telephoto") by standing far away from the subject, at any given F-# (e.g., F-2.8), you'll have a DoF of "X"; if you shoot the same image size moving close to the subject with a wide-angle lens, as long as you shoot at the same F-#, you will have the same DoF as you did previously.

CCD CMOS

Inasmuch as digital age is a blessing, it's also a curse as it make it so hard to explaine some concepts. I wonder how may new generation photographer ever built a pinhole shoebox camera...

For information about the possibilities of Canon CMOS sensors for your application, speak with an industrial imaging expert at Phase 1 Technology. Ask about an Evaluation Kit to test the unique capabilities of CMOS sensors from Canon.

CMOS cameras can have higher framerates than their CCD counterparts. This is because the reading of the pixels can be done faster than having to wait for a CCD’s charge transfer. This feature is essential for machine vision systems that often rely on real-time image processing for automation or image data analysis.

Depth of field (DOF) has to do with the areas of your image which are in focus or out of focus. Wide DOF = large area in focus. Shallow DOF = small area in focus. Take a look at the examples below.

Manufacturers are increasingly evaluating CMOS sensors for applications that once exclusively required the capabilities of the more costly CCD sensors. Due to their cost-effectiveness and growing capabilities, CMOS sensors are quickly becoming the preferred choice of machine vision camera manufacturers.

New to the industrial market, Canon offers several high-performance CMOS sensors. Among these is the 35MMFHDXS_A CMOS sensor featuring an enormous 19 µm pixels, which minimize noise and dark current and allow control over readout position and frame rate. The Canon 120MXS CMOS sensor delivers ultra-high 120 MP resolution in a compact design by incorporating close to the same number of pixels as photoreceptors in the human eye. Then there’s Canon’s 3U5MGXSBA Global Shutter 5 MP CMOS sensor, which offers fast, distortion-free image capture in a 2/3″ format, lower power consumption, and enhanced sensitivity.

RGB-NIR (Near Infrared) pixel filter options are available. Canon replaced one of the green filters on the sensor with an NIR filter, which gives the sensors the ability to “see” outside the visible spectrum and enables machine vision systems to classify images on another level.

Landscape photographers (think Ansel Adams) tend to prefer Wide DOF because it renders the whole scene in focus. Portrait photographers (like myself) often tend to prefer Shallow DOF so that the viewer is drawn into the subject and the rest of the background becomes a blur.

With innovations such as Canon’s, CMOS sensors will be a key part of the future of machine vision. Expanded applications, such as driver assistance systems, lending vision to advanced machine learning algorithms, and enhancing the function of augmented reality, are possible thanks to the CMOS sensor’s growing capabilities, compact size, and lower costs.

cmosccd区别

To learn more about those factors, you can watch the next movie in my course - click here to check it out.  As an important side note, you'll need to be a member of lynda.com to view that movie, but don't worry, if you aren't a member you can always sign up for a free 15 day trial by clicking here.

Modern cameras have decreased in size thanks to the growing capabilities of the CMOS sensor. Featuring previously unheard-of resolutions, low-light sensitivity, on-pixel innovations, and RGB-NIR color filter array options, CMOS sensors are taking the place of CCD for the manufacture of cameras and imaging solutions for the majority of industrial, medical and scientific applications.