What is the difference between a pinhole camera and a slr camera?

Answer 1

Most photographers would consider an slr to be "normal". If it's not an slr or a tlr, then you must be referring to a range finder camera or monorail camera. I presume range finder. Thus the major difference is that an slr system presents to the viewing eye pretty much everything that the lens is bringing to the film (minus the parts where the circular image lies outside the film rectangle). A range finder attempts to do this with a separate small viewing lens usually mounted on the camera face off to one side of the lens. The angle of view of the main lens is not the same as the angle of view of the viewing lens, which is usually not a problem. But if you are close enough to a subject such as a flower and you place the camera according to what you see in the viewfinder, you will be too far off to one side and will get less than the whole flower in the picture. This effect is known as parallax.

Answer 2

The main difference is that a pinhole camera has exactly that a pinhole and not a lens which an slr uses. Pinhole camera exposures are very long and not practicle in use.