The hoya 80b hoya multi coated hmc glass filter is blue it is used to balance daylight film under artificial tungsten or standard household incandescent lighting youve been given a project to do some slide copying on a copy stand unfortunately you only have daylight film and you notice that the copy stand is loaded with 3400k photofloods not to worry an 80b is a strong dark blue filter that will balance your colours back to reasonable normality this filter can also be used as a co