39. RANGEFINDER FOCUSING

ONE OF THE most precise methods of manually focusing is by using a rangefinder. This system is based on viewing a subject through two separate windows to determine its distance from the camera. This very precise optical system is both fast and easy to use in the field.

Rangefinder cameras are not common these days, but one manufacturer, Leica, makes both film and digital versions that are coveted by a loyal following. For film users, there are still plenty of rangefinder cameras available on the used market, since they were once the most popular style of portable camera.

The rangefinder system is based on two separate windows pointing at the same subject, with the viewing and framing done through the viewfinder window (Figure 39.1). A second rangefinder window is used for providing focus information that is relayed to the primary viewfinder.

When looking through the viewfinder window, a bright patch in the middle shows your subject as seen by both windows. If the lens is not focused correctly, you will see a double image (Figure 39.2). Turn the lens so the images overlap to become a single image (Figure 39.3). This system works well for subjects with contrast and particularly well with vertical lines. It’s very easy for the human eye to align two vertical lines, so the results are very accurate.

The rangefinder system has a long history and has been useful for many applications over the years including surveying, navigation, ballistics, and even golf. In the photographic industry, the rangefinder viewing and focusing systems were most common in the mid-20th century, often coupled with 35mm cameras. These portable cameras needed a precise way to focus the many lenses they could use. For many years it was the most accurate way of determining a subject’s distance from the camera. Photographers found this useful because of its accuracy, speed, and small size. An additional benefit was that the viewfinder window could show you the expected frame lines, as well as the area outside those lines. Being able to see outside the frame was a huge advantage for anticipating subject movement and seeing compositional options.

39.1 A rangefinder camera uses two windows for rangefinder focusing.

While Leica did not invent the rangefinder, their name is synonymous with it, and its part of their legacy dating back to the 1930s. Their current line of rangefinder cameras maintains the same lens mount that was introduced in 1954. The rangefinder camera was the compact standard and was produced by many manufacturers including Nikon, Canon, Contax, Fujica, Olympus, and others. New rangefinder cameras are not common, but do seem to pop up from time to time.

Properly focusing a rangefinder is very easy, so long as the system is properly aligned. Just turn the lens until you don’t see a double image in the focus area. Any error in the system’s alignment will cause all photos to be out of focus. Fixing a faulty system is not easy and usually requires a technician. It is also important to keep both windows clean; fingerprints will blur the subject and focusing will become difficult. Since the windows are aligned on a horizontal plane, it makes focusing horizontal lines difficult. You can turn the camera vertically to make those horizontal lines vertical, and thus, easier to work with.

There are many downsides to focusing with a rangefinder camera, most of which involve not seeing what the actual lens can see. Viewing through a separate window means that you can’t see the exact angle of view, which will cause parallax problems. These problems are more noticeable with telephoto and macro lenses. Inability to see filters and depth of field can be a serious detriment. The Single Lens Reflex (SLR) eventually superseded the rangefinder in popular use. However, a small contingent of rangefinder proponents continue to sing the rangefinder praises and carry on the tradition.

39.2 The rangefinder viewfinder will show objects that are not focused properly with two overlapping images on the focus patch in the middle of the frame.

39.3 When a rangefinder is correctly focused, the focus patch in the middle of the finder will show a perfectly aligned image.