By measuring the transmission through an antiferroelectric liquid crystal device (placed between crossed polarizers) as a function of both orientation and applied field in the so-called electroclinic-like, pretransitional regime the behaviour of the effective optic axis tilt angle (psi) and effective optic anisotropy (Delta n) is determined. The relatively poor alignment obtained in antiferroelectric liquid crystal devices is allowed for in the data interpretation and high quality results are presented.