On Lippmann's Photography

. This paper revisits the problem of recording of photographs using ultra-fine grain recording materials backed by a reflecting surface. A discussion is given of the underlying theoretical concepts and practical recording limitations and an explanation is given of the ability of the method to work with relatively narrow band (0.03 p) natural light. A simple practical experiment helps to clarify the underlying physical difficulties and provides an evaluatory method for the recording emulsion. An important necessary criterion associated with the recording optics is verified. A discussion of the use of Lippmann's technique to produce holograms in natural light emphasizes the difficulty of the exercise.