How To Make Sense Of Sensor Size

Digital Sensor Size Is As Important As The Number Of Megapixels

Oct 7, 2008

Photographers overlook sensor size when comparing compact digital cameras, concentrating on megapixels instead. This may be because sensor sizes are hard to understand.

The sensor size specifications for compact digital cameras are confusing as they are based on old-fashioned type classifications originally applied to Vidicon tubes in TV cameras.

The small CCD sensors in compact digital cameras end up with old-fashioned imperial fractions of an inch specification, indirectly representing the size of the sensor. Even though it may look like a measurement, it is a type, not a measurement. In these cases, a larger number in the bottom of the fraction is really a smaller sensor. For example, the Canon Powershot A470 has 1/2.3 inch type sensor while the Nikon Coolpix P6000’s 1/1.7 inch type sensor is larger, as indicated in figure 1.

DSLR look alike cameras come with the same or similar megapixel count as more expensive DSLR’s so why pay more? The Fujifilm FinePix S2000HD has 10-megapixel sensor, it comes with a wide range zoom and is available for $ 259.95. However the Fine Pix’s sensor is a 1/2.3-inch type much, much smaller than a 10 megapixel DSLR APS-C sensor.

Megapixels Are Only Part Of The Story.

Digital cameras with the same number of megapixels can produce very different image quality. A large sensor results in large individual pixels- in old film days large negative sizes resulted in better images and this carries over to digital cameras. The top digital image quality comes from medium format cameras with large sensors from manufacturers such as Hasselblad, PhaseOne, Mamiya and others – not the popular picks of Nikon and Canon pro models.

Larger Pixels.

One key factor is the size of the individual pixels, because with a greater surface area large pixels collect more light giving better picture quality with less noise. Manufacturers try to compensate for the inherent noise in pictures taken in low light conditions but often this can be counterproductive as excessive noise reduction destroys fine detail – giving as smeary or plastic look. A series of comparison images at DP Review illustrates the noise performance of compact cameras with different size sensors. Compact digital cameras produce good images under the right conditions, but as the lighting becomes less than perfect, they struggle to cope.

Full Frame DSLR Versus APS-C

While there is a big difference between compact Point and Shoot digital cameras and DSLRs, the comparison between APS-C and Full Frame DSLRs is almost irrelevant as far as picture quality goes. The main consideration is the limited angle of view of APS-C sensors compared to full frame sensors. The large difference in sensor size between APS-C and Full Frame DSLR sensors is offset to degree by the reduced angle of view of APS-C DSLRs, they only use part of the image that a full frame DSLR uses, and this is known as the crop factor.

Consider More Than One Factor

Photographers using only one characteristic when comparing digital cameras do not really get the full story of the camera’s performance. Sensor size and megapixel count are important, so is the design of the sensor, as advancing technology makes individual pixels smaller yet able to efficiently and accurately convert the incoming light into the electrical signals used to create digital images.

The copyright of the article How To Make Sense Of Sensor Size in Digital Photography is owned by Philip Northeast. Permission to republish How To Make Sense Of Sensor Size in print or online must be granted by the author in writing.