lens.

The main reason is that:
Inside the camera, a real image is formed on the film.
Also, for a virtual image, the light rays cannot sharply focus on the film (as shown in the diagram, the rays are divergent in such case) to form a clear image on it, therefore resulting in a blurred image.
N.B. An analogy can be taken for comparison between a human eye and a camera that the retina of our eyes is equivalent to the film on the camera. In the mechanism of our seeing objects, the real and inverted image is focused on the retina.