Using a very narrow band (0.004-0.013 nm) Universal Bire-fringent Filter, Filter, rapidly turnable between 410 and 700 nm, and the vacuum telescope at the observatory, we have developed photographic and video techniques to observe solar magnetic and velocity fields utilizing the Zeeman and Doppler effects respectively. This is in addition to direct filter-grams which can also be obtained at any wavelength in this wavelength region. The video technique permits virtually real time display. Both techniques are used for time lapse cinematography of solar activity.
Jacques M. Becker,
"Cinematography of Solar Intensity, Velocity, and Magnetic Fields," Optical Engineering 14(1), 140164 (1 February 1975). https://doi.org/10.1117/12.7971767