Measuring the image quality of digital-camera sensors by a ping-pong ball

In this work, we present a low-cost experimental setup to evaluate the image quality of digital-camera sensors, which can be implemented in undergraduate and postgraduate teaching. The method consists of evaluating the modulation transfer function (MTF) of digital-camera sensors by speckle patterns using a ping-pong ball as a diffuser, with two handmade circular apertures acting as input and output ports, respectively. To specify the spatial-frequency content of the speckle pattern, it is necessary to use an aperture; for this, we made a slit in a piece of black cardboard. First, the MTF of a digital-camera sensor was calculated using the ping-pong ball and the handmade slit, and then the MTF was calculated using an integrating sphere and a high-quality steel slit. Finally, the results achieved with both experimental setups were compared, showing a similar MTF in both cases

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