This nearly medium blue B&W KB 6 82mm Cooling Color Conversion Glass filter neutralizes the strong red tendency of light at sunrise or sunset out in the open when the original colors of the subject are wanted instead of a warm morning or evening mood.
In addition, the KB 6 filter is ideal for "under-corrected" filtering of artificial light photographs on color negative films. When filtration is performed only later during printing, there is a visible color shift and full correction leads to a higher loss of light.
An 80D filter is the least "powerful" of the 80 series. When using daylight film and you'd like to leave even more yellow than if you were using and 80C filter, the 80D is the way to go. An 80D doesn't bring the temperature up to daylight as much as an 80A, B or C.This filter allows you to somewhat "balance," i.e. bring back, correct color tone to your images. There is some loss of film speed that may require the use of a tripod but, at least, your photos will demonstrate the proper tonality they so richly deserve.