Resolution in pixels is not the only measure of image quality
A larger sensor with the same number of pixels generally produces a better image than a smaller
one. This is because each pixel on a larger surface area (given the same resolution/megapixel count). And the larger the size of each pixel, the more light, color and dynamic range can it capture. A full frame sensor has the biggest advantage, since its surface area is 36x24mm or
864mm2, compared to an APS-C sensor whose surface area is 22.8x14.9mm or 332.3mm2
Nearly all of us use, or have used cameras at some point in our lives, even if only on our cellphones. But how many of us really know much about image sensors, the heart of the image producing mechanism inside any camera?
Sensor…What is it ?
An image sensor is a device that converts an optical image into an electronic signal .
Most digital still cameras use either :
- CCD image sensor
- CMOS sensor
New trend is High Sensitivity Sensors. Also used in Canon HS cameras and
in DSLR to achieve less noise at high ISOs, thereby increasing the versatility of the camera, to achieve optimal results in a variety of shooting conditions.
Note: Image quality is a combination of Pixel count and Pixel size.
Pixel size plays a very important role in the quality of the image.
Lets take an example:
Camera Model Sensor Size Pixel Size
EOS 600 D APS-C 4.3 x 4.3 µm
S100 1/1.7 inch 1.86 x 1.86 µm
IXUS 115 1/ 2.3 inch 1.7 x 1.7 µm
Light does not just fall on a camera sensor. It is accurately directed there, but tiny lenses called Microlenses. These microlenses are placed on top of the sensor, and divert light on to the photo sensitive regions of the sensor.
Blur Effect
Note: To get beautiful Blur effect on the image, the size of the sensor matters. However it may not be considered as only variable that affect Depth of Field.
Three variables that do affect Depth of Field are:
1. Focal length
2. Distance to subject
3. Aperture value
Finally to summarize significance of Sensor size in photography
• S/N Ratio Improvement – Lower Noise
• Improved Sensor Sensitivity – High ISO
• Background Blur - DOF or "Bokeh" effect
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