Rochester Optical Co. (Rochester, NY)
R.O.C.'s Drop Shutter - c. 1885-c.1890's
Illustrated Catalogue of Photographic Apparatus,
C.H. Codman & Co. (Boston, MA), June 1886, p. 16
Notes: Like
many drop shutters, R.O.C.'s Drop Shutter is meant to press onto
the front of a lens; the ad even tells which lenses it is designed to
fit.
Directions:
-Install by pressing it on the lens 90 ½
counter-clockwise from what is shown in the image above, the wooden
handle uppermost.
-Prepare it by pulling the long black piece all the way up until the
brass piece catches in the notch visible at the left. The lens is
covered by the bottom of the slider.
-Pull the plate holder's dark slide out.
---If an
instantaneous exposure is desired, press and hold down the brass trip
lever. The black slider falls all the way down; the hole in the
slider drops past the lens and makes the exposure.
---If a longer, or bulb-type exposure is desired, the brass
trip level is pressed but immediately released; the slider then catches
a notch halfway down that leaves the lens open until the brass lever is
pressed again to send the slider all the way down.
The hourglass shape of the exposure hole was thought to make the exposure more even over the plate. Other drop shutters had square or rectangular holes, were made all or partly out of metal, or used rubber bands or springs to increase the speed of the drop (and decrease the time of exposure).
References:
Illustrated Catalogue of Photographic Apparatus,
C.H. Codman & Co. (Boston, MA), June 1886, p. 16
