A cinematographer is the author of the final version of the visual component of an audiovisual work. The first International Congress of Cinematographers, meeting at Huelva in Spain in 2004, issued a declaration stating that cinematographers are the lawful co-authors of the whole of an audiovisual work. As part of their creative and dramaturgical work, they select appropriate material reality for recording and, by the skilled use of the expressive techniques of audiovisual photography, they raise the emotional impact of that reality as part of the overall dramaturgical concept of the audiovisual work. These techniques include, in particular: the use of light and colour in creating the picture, the organisation of the material content in the given format of picture, different possibilities of perspective, definition and distortion offered by the lens, use of space, colour, and depth of field in the composition, camera angle, techniques related to movement, and other specially selected approaches. As a consequence of these creative techniques the resulting audiovisual work does not only make use of material reality, objects or persons, and their reactions in themselves, but also of the image of them created by the activities of the cinematographer as described above. In order for cinematographers to realise their artistic aims and ideas they need to have the necessary technical knowledge and organising ability. In addition to professional and technological knowledge, they need to have the ability to marshal their store of theoretical knowledge in a logical way, the ability to think both analytically and synthetically, a sense of formal exactness and precision, a feel for combination, quick-wittedness, and the ability to comply with the main artistic goals and cooperate with other colleagues who play a creative role – especially the director. Cinematographers' organising ability must be backed up by knowledge of psychology and the ability to lead a small team, together with the ability to make decisions quickly and responsibly in crisis situations when a large number of people are present. The combination of all these demands on cinematographers during film-making constitutes an enormous psychological burden. In terms of responsibility, the cinematographer is answerable to the director for the artistic value of the visual side of the audiovisual work, and to the producer for the technical quality of the photography in terms of its further reproduction. Cinematographers are bound to respect the statutes of the trade-union and professional organisation the Association of Czech Cinematographers if they are members of it.