A controlled-contact method of measuring an insertion loss of a compressible DUT having a first ferrule with a first optical fiber and a first end face is disclosed. The method utilizes a compressible reference connector having a second ferrule with a second optical fiber and a second end face. The method includes: axially aligning the first and second ferrules to define a gap with an axial gap distance of greater than 150 μm; moving the reference connector at a connector velocity in the range from 1 mm/s to 5 mm/s; when the gap distance is less than 150 μm, reducing the connector velocity to between 10 μm/s and 500 μm/s until contact while continuing to measure the coupled optical power; after contact, increasing the connector velocity as the reference and DUT connector axially compress. The insertion loss is determined from ongoing measurements of the coupled optical power.