|QL mechanism on Canonet QL19E|
image by Süleyman Demir (Image rights)
QL (which means 'quick loading') is a Canon designed film loading method which eliminates the need for the photographer to thread the film into the take-up spool. The film is simply laid into the camera back, with its tongue aligned above a reference mark. As the back is closed, a plate swings into place pinning the film in position to engage its sprocket holes. When wound, the film then threads onto the take-up spool automatically.
The QL feature was used in older bodies such as the FT QL and FTb QL. A similar concept was introduced in AL-1 QL (1982) and the more popular T series models from the program-only Canon T-50 in 1983 (Other T-60 in 1991).