The X-ray photoemission (ESCA or XPS) and the UV photoemission (UPS) techniques have been applied to the study of the 4 f electrons in clean samples of the following rare earths, Nd, Sm, Eu, Gd, Dy, Er, and Yb. For comparison the element Ba has also been included. The UPS method gives a higher resolution while the XPS method has the advantage of probing deeper below the Fermi level allowing also core levels to be studied. The oscillator strength for exciting 4 f electrons is very small for low photon energies. However, it increases rapidly with photon energy which makes the XPS technique very favourable to study these levels. The recorded spectra show a simple shape for elements with a half-filled (Eu, Gd) or filled (Yb) 4 f subshell while the spectra for the other elements exhibit a more complicated and extended structure. An interpretation of this is given in terms of multiplet splitting of the final state involved in the photoemission process