The QSI 520 model camera employs a 2 megapixel Kodak interline transfer CCD image sensor with microlens technology. The high quantum efficiency, wide dynamic range and low noise performance make the QSI 520 ideally suited to a broad range of demanding astronomical, scientific and industrial imaging applications. Electronic ShutterAll 520 models utilize the electronic shutter built into the KAI-2020M CCD image sensor to control exposures. Shutter timing is very precise and can range from as short as 100 microseconds up to 240 minutes. Mechanical Shutter The Model 520ws camera includes the internal mechanical shutter. When operating with an interline transfer CCD, a mechanical shutter is not used to actually make the exposure. This is still the responsibility of the electronic shutter. The mechanical shutter is employed to cover the CCD and simplify the creation of Dark and Bias frames for subsequent image processing. 520ws adds Internal Colour Filter Wheel The Model 520ws adds an internal five position filter wheel to the camera in the 'full-size' camera body. The filter wheel accepts any standard 1.25 inches filter. Various filter configurations are available