Film plane indicator @
The film plane indicator (-e-)is engraved in white on the top deck just behind the shutter speed dial. It indicates the exact position of the film plane inside the camera . Whenever it becomes necessary to measure the exact distance between the subject and film plane, such as in macrophotography, use the film plane indicator . The distance between the film plane and the lens mounting flange ® is exactly 46.5mm.
Infrared focusing index
The red dot beside the focusing index on most lenses is the infrared focusing index. When shooting with black-and-white infrared film, it is necessary to refocus 31 the lens to compensate for the fact that infrared light rays focus at a point slightly in front of visible light. To use the index, first focus on your subject through the viewfinder. Then look at the lens and take note of the focused dis- tance . Finally reset the focusing ring so that the desired distance is aligned with the red dot.