Rare Cameras > Lancaster 'Rover' Detective Camera 1891 (5) > Lens & shutter
The lens is mounted on a removeable wooden board in a Lancaster Patent 'See-Saw' brass shutter mechanism (so engraved on the face plate). The shutter has two 'V' shaped blades which open in a diamond pattern fronm the centre and then close as the trigger is moved in either direction. Speeds depend entirely on the speed of your finger as there is no spring mechanism. The earlier (I think) version has the engraving in plain upper case lettering while the later version shown here (with the drop plate thumb lever) has script lettering and has a flip over stop on the face of the shutter, which allows you to cancel the see-saw action in favour of an 'open-shut' action for long exposures.
The lens itself appears to be a single cemented doublet and the aperture diaphragm in front has eight curved blades with three positions marked - 10 (wide open), 20 and 30, although a fourth smaller aperture is also possible.
