The yellow splitter patch on a rangefinder camera aids in low light focus.
Many models of Yashica rangefinder cameras do not allow the user to focus through the lens; instead, the photographer looks through a rangefinder mechanism that is independent of the lens and film recording mechanisms. To assist in photographing in low light conditions, a yellow secondary image overlays the center of the rangefinder optics. To focus the camera, the yellow secondary image must align with the clear primary image. In older cameras, this patch is prone to fading as the prism in the rangefinder becomes dim with age. A faded yellow patch makes it difficult to focus in low light conditions.
Instructions
1. Take the rangefinder outdoors on a bright, sunny day and look through the eyepiece. Examine the image that you see to determine the size and shape of the yellow patch in the viewfinder window.
2. Cut out a dot of black tape with a detail knife that is the same size and shape as the yellow patch.
3. Place the dot of black tape directly onto the viewfinder on the front of the camera. The black tape will block the primary viewfinder image and allow the secondary image in the yellow patch to appear clearer.
Tags: yellow patch, black tape, secondary image, light conditions, shape yellow, shape yellow patch