Phase Retrieval (PR) techniques provide a complimentary approach to Digital Holography (DH) for estimating the complex amplitude of a wavefield. If one uses a Gerchberg-Saxon type iterative approach, generally two intensity distributions at different optical planes are captured. Fast Fourier Transform (FFT) based algorithms are then employed to iteratively recover the phase information. Once we have estimated the complex amplitude of the wavefield we can use numerical propagation algorithms to calculate the distribution at any optical plane. We expect however that the finite size of the camera aperture and the sampling effect introduced by the camera pixels will act to reduce the performance of the optical system. In this manuscript we attempt to examine these performance limiting factors in more detail using a special field as the input into our system; namely a speckle field. This particular type of field contains high spatial frequencies which in turn are related to the lateral speckle size. A series of PR experiments at different capture planes are conducted and we report on how the system performance is effected.