The feeling of presence of virtual entities is an important objective in virtual reality, teleconferencing, augmented reality, exposure therapy and video games. Presence creates emotional involvement and supports intuitive and efficient interactions. As a feeling, presence is mostly measured via subjective questionnaire , but its validity is disputed. We introduce a new method to measure the contribution of several technical parameters toward presence. Its robustness stems from asking participant to rank contrasts rather than asking absolute values , and from the statistical analysis of repeated answers. We implemented this method in a user study where virtual entities were created with a handheld perspective corrected display. We evaluated the impact on two virtual entities' presence of four important parameters of digital visual stimuli: resolution , latency, frame rate and jitter. Results suggest that jitter and frame rate are critical for presence but not latency, and resolution depends on the explored entity.