Store the F2 with the shutter cocked or not ?
Many people have asked me if it is harmful to store the F2 with the shutter cocked or not. (Cocked is when the shutter is advanced in the ready to shoot position.) My answer is always yes, and that Nikon stated in every instruction manual not to leave the shutter cocked overnight. The reason is because there are two very fine precision springs inside the F2 that pull the shutter curtains. When the shutter is cocked, these springs are wound and tensioned. (When the shutter is released, these springs are unwound and untensioned.) The tensions of these two springs are carefully calibrated so that travel times of the two shutter curtains across the frame window are precisely matched. If these springs are left in the wound position for too long, then their tensions would degrade and when released they would pull the shutter curtains slower. Quite often, these two springs degrade differently, resulting in different first and second shutter curtains traval times and hence producing uneven exposures or total blackouts at very fast shutter speeds. Therefore users must break their old habit of cocking the shutter after every shot. Also, they must remember to manually trigger the shutter for the last shot when the F2 is mounted on a motor drive, as the MD automatically advances the film and cocks the shutter after every release.
Precision spring inside the F2 Nikon do not recommend leaving the F2 cocked overnight