From The Van Gogh Museum:
Vincent didn’t like portrait photography, and this also explains why there are so few photographs of him. Vincent thought that photographs lacked life, and much preferred painted portraits. In his work, he was primarily concerned with portraying the character of the subject. When Vincent was young, photography was still complicated and expensive. Louis Daguerre published his version of the photographic process in 1839, but it was nearly another fifty years before George Eastman introduced his instant Kodak camera, triggering a massive increase in amateur photography. The intriguing phenomenon of photography became a point of comparison for artists, including Van Gogh. Although he started off considering photography as being rather ‘mechanical’, he later relented in Arles:
‘Ah, what portraits we could make from life with photography and painting!’