Apparatuses, systems, method, reagents, and kits for conducting assays as well as process for their preparation ar described. They are particularly well suited for conducting automated analysis in a multi-well plate assay format. Also disclosed are systems, devices, and methods provided herein for using a CCD camera based system to generate measurements having reduced crosstalk between measurements of multiple spatially separated subjects. CCD camera based systems as provided herein use improved reference level clamping circuits configured to fully reset reference levels during CCD readout, thereby reducing a level of crosstalk between measurements.