2 internal aperture stops
Date: 1875-1900
Inventory Number: 2007-1-0359
Classification: Diaphragm
Subject:
Maker: German ?
Maker: American ?
Maker: French ?
User: Harvard College (founded 1636)
Cultural Region:
Dimensions:
large: 2.9 × 2.9 × 0.5 cm (1 1/8 × 1 1/8 × 3/16 in.)
Material:
Description:
This is an unmatched pair of aperture stops of the sort inserted into a tube. The larger one has a round aperture; the smaller a slit aperture. The brass is blackened.
Signedunsigned
Inscribedin orange paint on the round stop: H
FunctionA diaphragm is a thin opaque structure with an opening (aperture) at its center. In optics, its role is to regulate the passage of light through a lens or optical system. It is sometimes called an "aperture stop" (or just "stop"). It can have an aperture of fixed size or one of adjustable size. A common form of the latter is the iris diaphragm.