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What is a digital sensor?                                                                                                              


Digital Sensor

Digital sensors are the electronic equilavent of camera film. They use tiny electronic components called photodiodes that allow an electrical current to flow when light is placed upon them. To make a photodiode react faster to light you must electrically increase its sensitivity. So in digital sensors ISO sensitivity is emulated, and thus allows us to change the ISO settings in the camera. An obvious advantage to this is that we can do it on a per image basis and not have to change a roll of film.

Just like with camera film though, this advantage comes at a price: noise
Essentially, the more you increase the sensitivity of the sensor, the more electrical noise you introduce into the signal.
It’s a bit like your old TV having a bad signal. The picture is fuzzy because of noise generated by electrical interference in the atmosphere.

Noise is worse with cheaper sensors, and better with more expensive ones. Noise is also better on larger sensors. However, digital camera manufacturers are making huge advances with reducing noise.

There is also a lot of good software out there that can reduce noise in an image, although it does soften and degrade the image. Cheaper sensors can suffer from colour noise, which is a lot worse.

Noise is more noticeable on computer screens and when making large prints (depending on the quality of the noise). It’s also more noticeable in dark images, or black parts of your photo. To minimise this and get smoother, cleaner images - especially in the shadows - you can use a technique known as exposing to the right (ettr). To learn more about this, why not join me on one my workshops.
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