Which was not a problem during the evolution of film photography?

One thing that wasn’t an issue during the development of photography was knowing how to make a basic camera. The first camera - the camera obscura - had been around for centuries at that time. We knew how to take a lens and capture a photograph. The issue was making those photographs permanent. Once someone found a way to make the photographs permanent, the issue became how to take the photograph and make it develop quickly.

The first photographs took over ten hours to develop - fifteen at the least. No one wanted to sit still for fifteen hours while the film developed. Soon afterwards, the cameras began to develop the photo within 15 minutes. That was a turning point in the history of photography, but that’s for another question.