However, most fluorescent applications have low signal levels and are suited to a lower full well capacity. Full well should be considered if your sample level is very high (brightfield imaging), if your sample can get significantly brighter and change over time, or if you are attempting to image bright and dim objects in one image. Some cameras offer full wells up to 80,000 electrons, meaning extremely bright samples can still be displayed, whereas some are much lower (100-1000), meaning they are suited to lower signal levels. In different camera models or different modes in the same camera, these pixels have a different full well capacity, which is the maximum number of electrons they can store and still display as an image. Full Well Capacity and Dynamic RangeĪs photons are converted to electrons by a sensor pixel, the electrons are stored in the silicon substrate of the pixel, known as a ‘well’. Some important camera factors to consider before discussing bit depth are full well capacity and dynamic range. This process is the same for all camera technologies, but changes in each of these steps can optimize the end result. This conversion depends on the camera gain (how many electrons are required to change to a new grey level) and bit depth (number of available grey levels), and is displayed on the computer monitor. Photoelectrons are then converted into a voltage, and then digital grey levels. The quantum efficiency (QE) of the sensor dictates what percentage of photons are converted, our back-illuminated sCMOS cameras have a peak QE of 95%. Light (composed of photons) hits the sensor of a scientific camera (which is divided into millions of pixels) and is converted into photoelectrons. Figure 1: How an image is made with a scientific camera.
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