There's a really cracking documentary about photography on BBC Four at the moment, called Genius of Photography. The first programme looked at the historical origins of different photographic methods, and the social and artistic changes that it brought about. Like all good documentaries, it told me some things I didn't know before, and made me think about photography in a slightly different way.

For example, they explained the process of making daguerreotypes, and showed some examples, both from the 19th Century and contemporary images. I knew the name, but had never really considered how they were made. You have to expose a mirror-polished silver plate coated with a layer of silver halide to light, and then you exhibit the original plate after developing and fixing the image. Daguerreotypes are really the antithesis of modern, digital photography. The equipment is expensive and cumbersome, the developing and fixing process is labour intensive, not to mention the fact that it involves mercury vapour, for added peril. It requires a lot of skill, and to cap it all, you can't reproduce the image: the plate is the image, and cannot be duplicated or printed. But boy, are they beautiful.

I'd only ever seen still images of daguerreotypes, but watching film of people holding them, and seeing the images from different angles, you get a much better impression of their almost three-dimensional appearance than you do from a still reproduction. They also showed some contemporary daguerreotypes (you can see some lovely examples by Jerry Spagnoli here) which were really stunning, with a beautiful tonal range and an odd feeling of intimacy. Perhaps it's partly their rarity, uniqueness and the craft that has to go into making them that makes them feel so special.