Autumn Leaves of fall
Toronto. Falling leaves. Cold. Damp. Windy. November in the city and winter is about to rush in. As I write this post on the 1st, we are seeing our first snow flurries of the coming season.
Leaves have a lot to do with photography both in the aperture and the speed setting of film cameras.
The Waterhouse stop and the slot in the side of a lens were in time replaced with a diaphragm device whereby the rotation of a ring on the lens would vary the size of the aperture by causing a change in the diameter of the centre circle and thus control the amount of light hitting the sensitive media, the depth of field (what parts of the scene would be in or nearly in focus), and the look of out of focus secular light (the bokeh of the lens). This diaphragm device was composed of a series of leaves attached to the ring.
When the media for photography reached an in-camera speed calling for sub-second exposure outdoors, shutters became mandatory. They evolved into various designs including a leaf shutter which used a series of metal leaves, like the diaphragm. This time the leaves were tightly shut and when released, quickly opened fully then snapped shut once again.
The leaf shutter could be synchronized to operate a flash at any speed. Unfortunately its top speed was limited by physics – about 1/400th second for 35mm cameras. Also the ideal location was midway in each lens resulting in expensive lenses. Optionally the elements in front of the leaf shutter could be changed to vary a lens’s focal length slightly (before we had zoom lenses). As a result, leaf shutters were mostly used for mid price range 35mm cameras.
Note that the title of this post is a riff on the title of Tina Turner’s hit song “What’s Love Got To Do With It?” sung here by the lady herself
