Roland Barthes explores photography throughout Camera Lucida and tries to explain exactly what photography means and what it does for both a photographer and an observer. Barthes says that photography is aligned with death because the moment that is photographed can never happen again; it's gone from the world for good.

Photography can also be seen as an expression of love, because we take photos of what we care for and want to remember. Photography is the primary theme and main focus of the work. This doesn't mean that he idealizes it, though. He actually finds photography shocking or, in some ways, bad. He says that motionless images doesn't mean the people in the pictures don't move, "it means that they do not emerge, do not leave: they are anesthetized and fastened down, like butterflies."

Grief is another theme of the book. Barthes considers his mother, whose photographs he's looking at. He misses her and she won't ever be back again—all he has left are memories and photographs. But when he looks at pictures of her, there's a grief that exists even in the happy ones. Not only is she now dead but the person he's looking at will die in the future. Her life ends, the same way all lives eventually end, and he's aware of it. His grief for his mother is obvious throughout the text. Every picture he looks at of her is stuck in the past, is lifeless, doesn't help him feel her presence.

Barthes mentions history as the time when we weren't born; it's the time before we came into being. This is something that we can't comprehend in a real way because we never experienced it. When he talks about the history of his mother before he came into being, he discusses her clothes. They're clothes she wore before she gave birth to Roland. He says there's a stupefaction in seeing her dressed differently—because history is a kind of story that we don't have the right tools to fully comprehend.