Weston Invercone for a Weston Master V light meter
Sangamo Weston
Category
Photographic technology
Date
1963 - 1972
Materials
Plastic, Metal
Measurements
24 mm (Length); 55 mm (Diameter)
Collection
Fox Talbot Museum, Wiltshire
NT 1525601.2.1
Summary
Weston Invercone for a Weston Master V light meter This is a little chunk of white plastic which doesn't quite seem to fit but is in fact an extrordinary piece of design which has made the Weston the most accurate incident light meter in the world. The inverted cone shape is designed so that as the meter is angled to the light source, the readings remain accurate which they would not do if it were a dome. Because backlight effects the exposure, a small part of the invercone sticks-out beyond the top of the meter case to pick any such light up. Only problem is that you can't see the dial if you hold the meter with the invercone towards you as you would do if the light is coming from behind you - which it often does. The first meter to use an invercone is believed to be the Weston II.
Makers and roles
Sangamo Weston , manufacturer