Variations: Finger release at 7 o'clock or 11 o'clock; with or without pneumatic release.

Houghton and Butcher used the Ibso on their better quality hand cameras from about 1909. On this example there is a wheel with settings of Free, Lock and Open, this may have been special to Houghton. Normally the Ibso has C, B, and T settings on the shutter dial.