Digital Camera Sensor Size

Thinking about buying a high-end digital camera? Purchasing a quality digital camera today can be a daunting experience. Similar to the cellphones, tablets and laptops, advances in the technology for making camera and lenses is moving so rapidly, it makes zeroing in on a purchase seem like you are selecting a moving target. However, regardless of the type and style of camera you choose, or its feature set, the one single factor that determines a camera’s ability to capture great pictures is the size of its digital sensor. Hopefully this post will help you to better understand this all important feature and the options available to you.

Understanding Sensor Size: The size of sensor that a camera has ultimately determines how much light it uses to create an image. As noted in my post on APERTURE, capturing a great picture is not about selecting buttons and switches on a highly sophisticated camera or lens, it’s about seeing and capturing light. Without light, there is no photograph. In very simple terms, image sensors are the digital equivalent of film. They consist of millions of light-sensitive spots called photosites which are used to record information about what is seen through the lens. Therefore, it stands to reason that a bigger sensor can gain more information than a smaller one and produce better images. Able to gain more information, the large sensor would be capable of turning out photos with better dynamic range, less noise and improved low light performance over that of a smaller sensor.                       Another thing to understand is that sensor size relates to capture size. As a sensor reduces in size, it captures image data from a smaller area than a 35 mm film SLR camera would, effectively cropping out the corners and sides that would be captured by the 36 mm × 24 mm 'full-size' film frame. This is called crop factor and is related to the ratio of the dimensions of a camera's imaging area compared to a reference format; most often, this term is applied to digital cameras, relative to 35 mm film format as a reference. The term crop factor was coined in recent years in an attempt to help 35 mm film format SLR photographers understand how their existing ranges of lenses would perform on newly introduced DSLR cameras which had sensors smaller than the 35 mm film format, but often utilized existing 35 mm film format SLR lens mounts.Because of this crop, the effective field of view (FOV) is reduced by a factor proportional to the ratio between the smaller sensor size and the 35 mm film format (reference) size.                       So, larger sensors can help you capture better quality images, but as you can see from above, they bring with them a number of other characteristics, some good and some bad. Another obvious impact of a bigger camera sensor is that of size; not only will the sensor take up more room in your device, but it will also require a bigger lens to cast an image over it. Bigger sensors can also be better for isolating a subject in focus while having the rest of the image blurred. This usually meant a bigger and heavier camera, however, the good news here is that camera manufacturers are coming up with ways to put larger sensors into smaller cameras.

Types of Sensors: There are only two basic types of sensors, CCD and CMOS. CCD stands for ‘charge-coupled device’.  CCD sensors are renowned for creating the highest quality, lowest noise images, however, they consume 100x the battery power of a CMOS sensor. CMOS stands for ‘complementary metal oxide semiconductor’. They are considerably cheaper to produce than CCD sensors and are faster at reading the information gathered when you open your shutter and expose it to light. Furthermore, they are known to suck up less power from your battery, thus enhancing battery life. Beyond this, sensors are classified by their physical size, which most often determines the size and classification of the camera that the are found in. Let’s review the options generally available.

Full-Frame DSLR Camera: These are ILC, “inter-changeable lens” cameras with a  "D" (digital) electronic image sensor sensor that is equal in size (measuring 36 x 24mm) to that of the negative frame found on a roll of 35mm film. The "SLR" stands for single-lens reflex. This is a camera that typically uses a mirror and prism system (hence "reflex", from the mirror's reflection) that permits the photographer to view through the lens and see exactly what will be captured, contrary to viewfinder cameras where the image could be significantly different from what will be captured.  Though these cameras are generally the largest and heaviest, advances in electronics and technology are help to reduce their footprint. Full-Frame Fixed Lens Digital Compact (DC): Though not a SLR camera, Sony’s new DSC-RX1 if the only digital compact camera with a Full-Frame sensor. It, however, in not a ILC and comes with a Zeiss 35mm f2 lens. Though obviously much smaller than a DLSR, the asking price of this new camera is approximately $2,700.00.   APS-C DSLR Camera: Unless specifically specified as a “Full-Frame” DSLR, most DSLR’s use sensors measuring approximately 24 x 16mm, called APS-C sensors. The actual size of APS-C sensors in DSLR Cameras varies by manufacturer. Nikon DX, Pentax, Sony APS-C sensors are 23.6 x15.7mm. Canon APS-C sensors are 22.2x14.8mm; though they do have a larger APS-H sensor that is 28.7x19mm. APS-C DSLR Camera w/LCD/Optical/Electronic View Finders(EVF): These cameras can have an LCD screen with Live View, an optical viewfinder, an electronic viewfinder, or a combination of these. Many newer DSLR cameras now come with LCD screens with Live View, in addition to an optical or electronic eye-level viewfinder. EVFs overcome the problem of your viewfinder and camera seeing slightly different things by giving you an exact picture of the scene you’re photographing in the viewfinder. This happens simply by putting a little LCD in the viewfinder. APS-C Interchangeable Len Compact (ILC) w/EVF or OVF (built in or available): or APS-C Fixed Lens Digital Compact (DC): It is important to note that there are many smaller, non-DSLR high-end compact cameras available today that offer a APS-C sized sensor. Mirrorless Four-Thirds/Micro Four-Thirds ILC w/LCD/Electronic View Finders: These smaller Four-Thirds cameras use a digital electronic image sensor sensor that, at 17.3x13mm, is slightly smaller than a APS-C sensor. Low-end Point & Shoot Cameras: Obviously, due more to a low price point than the size of the camera, the cheaper sensors in low-end cameras become much smaller. Cell Phone Cameras: Most smartphones, including the iPhone 5 use a tiny 1/3.2-inch image sensor. In real terms this measures just 4.54 x 3.42 mm and explains how they are able to keep devices so slim and light, but also why image quality and low light performance suffers, especially when they can have as many as 12 megapixels. The HTC One uses a slightly larger 1/3-inch sensor (4.8 x 3.6 mm) and fewer pixels to combat this. The Nokia 808, with a 1/1.2-inch sensor (10.67 x 8 mm), was undisputed king of smartphone sensors. However, the recent announcement from Nokia about its Lumia 1020 smartphone with its 41 megapixel camera with a 1/1.5-inch image sensor that uses a Zeiss-branded lens with six elements, with a maximum aperture of f/2.2 is the new game changer. With close to three times the area of the sensors in most compact cameras, and more than five times the area of typical camera phone imagers, this camera phone should be affecting every digital camera offering right up the line over the next year.

Summary: Obviously, many physical aspects contribute to making a quality picture; from the quality and speed of the lens and the number of its elements, the size of the sensor, the number of megapixels “crammed” onto the sensor, RAW capture, to the camera’s built-in ability to perform focusing, apply anti-shake, and algorithms designed to perform post “clean-up” of the image. One thing still remains true, the larger the image sensor is, as it relates to all of these aspects, the better the final result will be.