Our recent investigations of the magnetostatic properties of Tb2Ir2O7 and Er2Ir2O7 put into evidence different magnetic behaviours of Tb and Er in these iridate pyrochlores. The Ir-5d electrons exhibit a metal-insulator transition accompanied with a magnetic freezing at 130 K in Tb2Ir2O7 and 140 K in Er2Ir2O7. This magnetic freezing induces an "all-in all-out" magnetic order of the Tb moments in Tb2Ir2O7 through the f-d exchange. In contrast, no Er magnetic order is detected by neutron diffraction in Er2Ir2O7 down to 2K. We understand this by modelling the Tb magnetism with multi-axial Ising spins (aligned along the directions) and the Er magnetism with multi-planar XY spins (perpendicular to these directions). As to confirm and further our insights, we request 3 days beam time on IN5 and 3 days beam time on IN4 to probe the crystal field excitations in both Tb2Ir2O7 and Er2Ir2O7 and the magnetic excitations in the "all-in all-out" magnetic ordered phase in Tb2Ir2O7.