The Chinon 35 F-A uses the same flash and lens as the Chinon 35 F EE, but the shutter is slightly different. The huge difference between the two cameras is that, within the same size and weight, the 35 F-A is autofocus.

On each side of the viewfinder are located one or more LEDs. Even with the eye pressed to the viewfinder, they are perfectly visible. On the left, there is a green and a red LED. On the right, there is only one, which is orange. This last one is the flash charge indicator. When the shutter release is pressed, the red LED lights up (serving as an indicator of battery charge), then the green one when the autofocus is effective.

The viewfinder is collimated and has parallax correction. A frame that delimits the action field of the Visitronic automatic focusing system is also visible. When the shutter release button is pressed, simultaneously with the red LED lighting up in the viewfinder, a needle briefly positions itself in front of the pictogram representing a mountain, then it descends towards the logo corresponding to the required distance, while the green LED lights up. All that's left is to release the shutter. The Visitronic system has been improved since its release, as now, holding the shutter release halfway memorizes the distance and locks the setting.

The flash is synchronized at all speeds faster than 1/60th of a second.

The film winding and transport are ensured by operating the lever on the camera. Rewinding is also manual. Motorization of these functions is provided on the 35 F-AM model.

What is the Visitronic system?

The camera is equipped with five openings on the front: the lens, the cell window, the viewfinder, and two windows for the Visitronic system (also known as VA/F for Visitronic Auto/Focusing). These two windows are located on each side of the "Konica Auto Focus" inscription.

The system operates by triangulation, like a rangefinder, rather than by contrast analysis.

First, let's look at the VA/F assembly diagram in the C 35 AF (these photocopied diagrams come directly from Japan and the USA, annotated with felt-tip pen, re-photographed, filtered, retraced, and then photographed again as best as possible). From the subject (1), a mirror fixed at 45° (2) reflects an image into the VA/F (3). The rotating mirror (4), upon triggering, starts from the appropriate position it occupies for a subject located at 1.1 meters (approximately 43°) and rotates with perfect regularity to the position it occupies for a subject located at infinity (45°). During the rotation, the VA/F, which compares the two images reflected by the two mirrors, indicates (we'll see how and to what) the moment it detects that the two images on its two sensitive cells become identical. At this instant, the two beams converge on the subject. This is the principle of the rangefinder!... but classically, it is the eye that determines the moment of the superposition of the two images... whereas here, it is the VA/F that compares their identity.

At the moment the mirror (4) starts to rotate, the lens (5) begins to move back from the focus at 1.1 meters to the focus at infinity, under the action of the spring (6). Mirror and lens travel their course in exactly the same time.

 Returning to the VA/F, during the course, it indicates the moment of the identity of the two images to a "brain" (7). This instantly powers the electromagnet (8) which, by engaging the tilting pawl (9) in the rack (10) of the lens, stops its movement. The subject (1) is then in focus on the film (11).

Meanwhile, the automatic exposure meter measures the exposure, or in flash mode, the lens position controls the diaphragm, and the shutter release occurs. Because automatic EE exposure settings and VA/F focusing are ensured during the course of the shutter release! ± 1/30th of a second... A needle visible in a window to the right of the lens allows you to read, if desired, the setting used by the automatic focusing system (post-control).

During the next winding, the mirror and lens reposition themselves to 1.1 meters, waiting for the next analysis...

The VA/F is a set of integrated circuits and optics sold sealed to manufacturers who must associate the external components.

(Sources: Phot'Argus No. 83, November 1977)