Battery holder is a bit too big (especially the bottom dimensions) for my left hand to comfortably I reach and use the 12-40mm f2.8 pro lens mounted to the OM-1, so I leave it off for that. The 40-150mm f2.8 pro lens is easier to use with the battery grip, as it's controls are further forward on the barrel. However the ability to use the vertical grip controls in a similar manner as the horizontal grip is huge plus. See my review of the camera noted - that is a five star.