Therefore, a Bessel filter has to be created in such a way, that the filter response time (tF) together with the physical (tp) and electrical response time (te) of the individual opacimeter must result in the required overall response time (tAver).
Derfor er man nødt til at indføre et Bessel-filter, således at filterresponstiden (tF) sammen med den fysiske (tp) og elektriske (te) responstid af det enkelte opacimeter resulterer i den ønskede samlede responstid (tAver).