subject: Information about the Work of Rangefinder [print this page] Rangefinders are devices which are used mainly for cameras. They are used as the focusing mechanism. They are widely used in some different cameras with some different film formats. Therefore, you have to make sure that there is no problem with the focusing mechanism before deciding to buy one of the cameras.
Then, how does this rangefinder work? Mostly, cameras are equipped with three lenses which are to collect the light for focusing on the film plane. They are viewfinders, the main camera lenses which are to gather light for focusing on the film plane, and also separate lenses for gathering light as well as reflecting it to the overlay the image in the first lens by a mirrors and prism.
The prism of this mechanism is connected to the cam shaft of the lens. The prism will move in the rangefinder as the lens is moving to take the image to the focus on the plane of the film. While the prism and the lens are moving, the two images will either coincide or diverge in the viewfinder. If the two images are completely overlaid, the lens is in the right position and the image of the film plane is in focus.
However, the use of this rangefinder has pros and cons. The cons of this device include the image in viewfinder is counterbalance to the lens which can lead to parallax problem with the rangefinder. Parallax is known as the difference of what camera lens and photographer sees when the subject is getting close to the camera. Also, another weakness of rangefinder is the limited focal length of the usable lenses.
The strength of this rangefinder is that it has no momentary blackout as the mirror slowly moves up to let film exposure. It allows you to see the image in the viewfinder even when shutter is exposed to the film. In addition, it is commonly simpler and quieter than SLRs (Single Lens Reflex).
