The group used the camera to take 34 ten - minute exposures of a tiny section of the sky. (newscientist.com)
In each field they took 22 twenty - minute exposures spread over 14 months to find the variable stars and measure their periods and brightness. (hubblesite.org)
Matt used an autoguided Astro - Physics 130 EDF f / 6.7 refractor to obtain this color photograph, a 90 - minutes exposure on hypered Kodak PPF 400 film. (maa.clell.de)