The present invention relates to an optical transmission system and a channel assigning method with structure to reduce dispersion of power levels among signals dropped at respective signal branchpoints on an optical transmission line out of signals of multiple channels amplified in an optical amplifier. The window is covered by a closure that may be resealed to the pack body either through insertion of a tab on the closure into a tab receiving slot in the front wall of the pack or by applying a permanent package adhesion along the outer edges of the closure with the edges of the openings in the top wall and the front wall. The grooves have sharp edges, radiused ends, and a draft angle between about 2\xb0 and 12\xb0. Recovery filters corresponding to the capturing parameters, which is created by the photographing lens based on the image processing parameters, are received from the photographing lens, and stored in a memory.