Abstract: | The paper reviews the status of the optical transfer function (OTF) as a potential standard method for measuring the definition of photogrammetric camera lenses. The nature of the OTF and its relation to resolving power are explained. The limited success in obtaining agreement in international comparisons of OTF measurement and the programme of the Scientific Instrument Research Association group research project on the O TFare summarised. Some of the difficulties envisaged in applying the OTF as an ISP standard are discussed. |