Set of two interference filters used to study the strength of Hß absorption at 4861Å. The narrow band filter has a halfwidth (FWHM) of 3 nm and the wide band filter has a halfwidth of 15 nm. These two filters must be used together and are often used in conjunction with the Strömgren four-color filter set.
Optec offers a wide selection of filters for astronomical photometry in standard color systems. These filters are designed for the SSP series of single-channel stellar photometers and are 12.5mm (") in diameter and 7.00 mm thick. The filter sets offered are the Johnson U B V R I J H wide-band standard color set, Strmgren u v b y medium-band four-color set and the H wide & narrow band filter set.
To learn more about the Strmgren and H filters click here to download (1.8MB) and read a tutorial. Each of these filters can be factory mounted directly into the 2 and 6-position (automatic) filter sliders for the SSP photometers. See below for the transmission characteristics and instrument compatibility.
For routine photometry, consider a B - V set mounted in a two position slider. Consult texts on astronomical photometry for more information on the use of these special filters.
The Johnson filters that were available from Optec in 1-inch diameter size have been discontinued. Some may still be listed on the Scratch and Dent page. They have been replaced by a new Bessell design that are 5 mm thick and are similar in transmission to our 50 mm diameter Bessell set sold for the IFW.