This study investigated pre-service physics teachers' (PSPTs) misconceptions and conceptual difficulties about geometrical optics in the contexts of plane mirrors (single and hinged), spherical mirrors (concave and convex) and lenses (converging and diverging) using prolonged interviews and an open-ended test. The interviews were conducted in five sessions with a divergent sample of 16 PSPTs, and the open-ended geometrical optics test (OEGOT) was administered to a sample of 52 PSPTs in Turkey. The interview guide and the OEGOT included mainly qualitative questions, which were specifically designed to elicit and examine PSPTs' misconceptions about geometrical optics. Several misconceptions held by PSPTs were identified and discussed. We found that PSPTs mainly had difficulties with the ray model, the function of the observer in the real and virtual image formation and observation processes, and the function of the screen in image formation and observation processes. Also the misconceptions in plane mirrors were found to be more coherent and experience-based while the ones in spherical mirrors and lenses were fragmented and loosely held in nature and mostly based on instruction.