Dynamic Range Of Sensors

The dynamic range of any sensor used in digital cameras is defined by the largest possible signal divided by the smallest possible signal it can generate. The largest signal represents the maximum amount of light that can be converted by the sensor into a unique digital value that represents a pixel into a photo. The smallest signal represents the value generated by the sensor when it doesn’t receive any amount of light. It is also known as the “noise floor”. Cameras with a large dynamic range are able to capture shadow detail and highlight detail at the same time. Even the most advanced sensors today cannot compete with human eye in terms of dynamic range.

Dynamic Range

Dynamic Range

When shooting in JPEG, the tonal curves applied by the camera usually clip shadow and highlight detail which was present in the RAW data. RAW photos preserve the dynamic range of the sensor and allow you to compress the dynamic range and tonal range by applying a proper tonal curve so that the whole dynamic range is represented in a way that is pleasing to the eye.

A pixel in any digital sensor will convert the amount of light it receives into a value ranging from 0 to 255. These values of all the pixels will compound the final photography that you see on your display. If the amount of light that falls on a pixel is greater than the maximum corresponding number (255), the excess of information will be lost (clipped). The best analogy for this is a bucket that collects rain drops. The bucket is the pixel from the sensor and the rain drops are the light. When the bucket is full the excess of rain drops will be lost. Going back to our digital cameras and sensors, if we decrease the exposure time some of the details in the shadow areas will be lost.

The sensors in digital SLRs cameras are bigger than the ones in compact cameras, so each pixel will have a wider area that will capture light. This allows the pixel to capture more light, in the same amount of time. Now you can understand why sensors in digital SLRs cameras have bigger dynamic range.

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