Reflexive Viewing System

[deepak srinivasan]

I Managed to get a copy of a book written by Kris Malkiewicz called "CINEMATOGRAPHY" its 2nd Edition.

in this book in pg-5 under a subtopic called "Viewing Systems" i read about the shutters role in viewing system in cameras like arriflex & eclair. i want to know how this works in camera,

 

question-1

Will a person operating camera see the frame completely or inbtwn shutter close and open will be scene?

 

Question-2

He said abt a prism inbtwn lens and shutter and it need compensation, how dis works ?

i dint understand this because i dont have a picture in mind about have the mechanism of camera could be.

KINDLY HELP ME WITH IT.

[Ian Cooper]

1. With a "mirror shutter" viewing system, whilst the shutter is closed to the film the mirrored surface bounces the light into the viewfinder so the operator can see the image through the lens. Whilst the shutter is open to the film there is nothing in the path of the light, so nothing gets bounced to the viewfinder.

 

This viewfinder system will flicker whilst the camera is working, and depending on the design of camera may stop with the viewfinder blanked out (ie. with the shutter open). If this happens then you need to inch the motor round to close the shutter and regain a view through the viewfinder. This design has the advantage that there is nothing in the light path between the lens and the film whilst actually making an exposure.

 

 

2. With a prism viewing system there is a glass prism in the light path from the lens to the shutter. The prism will allow the majority of the light to pass straight through to the shutter and then film, but a small proportion of the light will be bounced off at an angle to the viewfinder.

 

Because the prism is always in the light path it means there will always be an image in the viewfinder and it will not flicker. The disadvantage is that there will always be a small proportion of the light which passes through the lens that gets diverted to the viewfinder and doesn't reach the film. The markings on the lens don't know some of the light passing through it won't reach the film. This is why you would need to manually compensate for the light loss. After all, if you put the same lens on a camera with a mirror shutter then there wouldn't be any loss at all.