On the recent period, higher financial and administrative barriers have been settled in many museums all over the world preventing amateur and professional photographers to take pictures of artworks ; museum picture library becoming the main way (if not the only way) to get reproduction of artworks. The purpose of this paper is to examine wether museum behavior is economically efficient or not. In other words, the question is to know who should own the reproduction rights on the photos taken of works of art exhibited in museums. We show that even it is efficient for museums to ask visitors to pay fees (club theory), discriminate visitors according the nature of their consumption (final or intermediary) decreases the social welfare. When museum ask higher fees to photographers, they get the consumer surplus but they lower the competition on a derivative market. We underline the costs of such a strategy. Beyond the social cost of the monopoly, we emphasize the loss of positive externalities (for the museum, the artist and the population) because of a lower viewing of artworks.