Well, since i watched this film I can say that a new perspective of art history has arisen in me because i have always had a high respect for those art works that delighted our eyes, but with new theories that David Hockney has presented i felt shocked but at the same time i fell motivated. The theories that Hockney pointed was the use of lenses and mirrors to create new paintins, this is called: camera obscura, a dark room just with a hole in one of its walls where the light of the image came through and reflected in a lens to a canvas. This way a huge amount of the artist's work was done because he got a perfect view of the picture outside down; after all this process was done the artist just traced the image and he got a perfect draw. this is why art in the past centuries was perfect, mot just in matters of drawing but in color too. Anybody can say that this was an easy job and that these artists were not master at all, but Hocknes shows that this requires a good amount of patience and knowledge about how to mix colors, so at the end this was not easy and still people who did this were masters.
In my opinion it was bad that art historians did not record this techniques, maybe because the fame of the masters at this time could be hurt and the people would not consider them as good as they think. i see the camera obscure as another tool for artist and not as a cheating device, maybe now it can be consider as that because it was hidden to the public.