Why don't they need a lens to focus the image?

To actually get an image where the film is, the lenses take the incoming light and focus it there.

If the lens does not focus the picture well, the photograph will be blurry.

As of August 2012 the lens can focus a single wavelength.

The physical basis of bloom is that, in the real world, lenses can never focus perfectly.

That is why lenses can focus light and magnify images.

Its light shone bright; at a touch, the lenses moved and focused.

It means, simply, that a lens focuses different colors of light differently.

The mirrors served as lenses to focus on their own dances (or they could even watch another person watching).

As if a lens had focused, the barrier seemed to materialize before him.