Series filters
Series filters are an older type of lens filter made in several different sizes or series. Many cameras and lenses from the 1930s through the late 1970 use Series Filters. These glass or optical resin filters are round usually in a metal mount distinguished by the absence of threads. Series Filters were an early attempt at standardization where a camera user could use one size of filter on similar sized lens from different manufacturers.
The filter is attached to the lens between two thread rings or a two-part lens hood to hold a series filter in place. Adapters were used to fit larger series-sized filter to lenses of smaller diameter. This advantageous aspect of series sized filters has been replaced by step-up and step-down rings.
The sizes in the series filters are identified by a number or by the diameter of the filter in millimetres (such as series 63 or 93). The number is usually in Roman numerals for integers and in Arabic numerals for half sizes. The series number is often stamped into the mount on their circumference. The progression of the integer sizes is in imperial .
The diameter of the filter for each series is:
Series Diameter (") Diameter (mm) IV 13/16 20.6 4.5 ~ 25.5 V 1 3/16 30.2 5.5 ~ 35.9 VI 1 5/8 41.3 VII 2 50.8 7.5 ~ 57.0 VIII 2 1/2 63.5 IX 3 1/4 82.6 X 4 1/2 114
References
- Warren, Bruce, 2001, Photography, Thomson Delmar Learning, ISBN 0766817776.
- Filter_(photography) at Wikipedia, this page incorporates material from the Wikipedia page on Oct 2, 2006
