The invention relates to a camera unit, comprising an image sensor (10), a mechanical shutter (16), a host module (12), and connections between them, in particular a data and control connection (D1, C1) between the image sensor and the host unit. In the image sensor (10), there is a photoelectric pixel matrix (101), a timing unit controlling it, an electronic shutter (ERS), and a ‘global reset’ circuit for resetting the pixels simultaneously. The said data and control connection comprises: a data connection (D1) based on a series bus, a control connection (C1) based on a series bus, and a global-reset signal connection (G1, G2) separate from these. The invention also relates to a method for controlling an image sensor in a camera unit.