Bulb is named for the bulb on detachable rubber pneumatic shutter releases that came with early cameras. With shutters set to "B", the pneumatic release kept the shutter open for as long as the photographer squeezed the bulb—a "Bulb" exposure.
The Bulb setting (abbreviated B) on camera shutters is a momentary-action mode that holds shutters open for as long as a photographer depresses the shutter-release button. The Bulb setting is distinct from shutter's Time (T) setting, which is an alternate-action mode where the shutter opens when the shutter-release button is pressed and released once, and closes when the button is actuated again.[1][2]
^Cite error: The named reference Stroebel_Zakia_1995 was invoked but never defined (see the help page).
^Cite error: The named reference Suess_2003 was invoked but never defined (see the help page).
&sq=&lang=&file=File:Conley_Model_C_folding_camera_(circa_1909).png)