For measurements close to the nailfold, movement can be reduced by gluing the fingernail to the restraint arm. One end of the restraint arm has been shaped to fit the curved surface of the finger nail. Apply one very small drop of 'nail adhesive' (Ethyl Cyanoacrylate) onto the finger nail. Lower the restraint arm down so that the shaped end of the arm is in contact with the finger nail. After about 20 seconds, a very strong bond will have formed. Carefully apply acetone to release the glue after the experiment. It may take several seconds for the acetone to weaken the bond.
Avoid acetone contact with the skin.
Rotate the CAM1 back into position.
Make sure the subject is comfortable and that the whole arm is well supported to reduce unwanted movements.
For imaging nailfold capillaries, position the finger with the illumination pointing at right angles to the finger. When the light is incident from the finger tip, there will be too much surface reflection from the curved surface.