As digital holographic microscopy (DHM) uses microscope objectives (MO) for enlarging the sample, some associated effects that are not present in optical microscopy have to be considered as quantitative phase imaging (QPI) is regarded. The remaining phase curvature introduced by the MO, which does not affect the optical microscopes, plays a determinant role in the performance of the DHM. In this contribution a thorough analysis of the physical parameters that control the appropriate utilization of MOs in DHM is presented. The analysis is carried for QPI. We study the sample phase perturbations that the MO phase curvature introduces. An analysis of the regular ways as these phase anomalies are removed is presented. The study is supported by means of numerical modeling and experimental results.