Camera Parts: Film Advance Lever
A film advance lever is one of the camera parts film cameras may possess but digital cameras do not. This is a part found in antique and vintage film cameras. For example, a Canon EOS 650, the first of the Canon EOS line introduced in the 1980s, does not have a film advance lever.
Film advance levers were found on all SLR film cameras when they first became popular. The normal location would be where the right thumb would sit on the top of the camera body, directly behind the shutter release button. A single pull would roll out the perfect amount of film so the next picture could be taken and exposed. Generally, they had gears inside so a pull would always pull out the same length of film no matter how hard the level was pulled. On high quality cameras, the workmanship was incredible, and they often work perfectly even 50 years later.
Eventually, film advance levers were replaced by motor drives.
Problems with Film Advance Levers
The most common problem would be if the gears wore out. Then, a single pull might not result in the same length of film being pulled. If too much film were pulled, the photographer would get fewer shots per roll. More commonly and more damaging, too little film would be pulled, resulting in overlapping exposures, ruining both shots. Also, the lever itself could break off, though this is less common.