by peterbone » Thu May 29, 2014 8:21 am
I assumed he used non-permanent pens so that he could reuse the same sheet, or maybe a few sheets for onion skinning. Once he's taken the photo he can wipe the sheet clean before drawing the next frame. I assume he used a tripod to keep the camera in the same position. He must have taken several photos of each frame and chose the one with the best position in each.