Monday, July 11, 2011


The iris in a Bolex Reflex (P series) cameras is located behind the optics for the viewfinder reflex mechanism. The iris itself is about 3/4 inch in front of the film gate; buried pretty deep. You can look through the viewfinder, close the iris and still see the subject.

The metering system receives light by means of a small mirror mounted at 45 degrees to the light entering the lens. At all times, its position is to reflect all light passing thru the iris into the CDS cell for metering. The metering system therefore, will indicate light affected by the iris.

When the camera is running, the mirror alternately moves back and forth for two functions:

1) exposing the film gate and allow light to reach the film, and

2) then blocking the film gate, while still sending all light to the CDS cell for metering.

When the camera is running:

1) you cannot see any 'flickering' in the viewfinder,

2)     you cannot 'stop down' to see DOF as with a 35 mm reflex still camera.

                            Copyright 2011

No comments:

Post a Comment