The 'Square' Transmission Curves of our Denkmeier Hi Def Filters that are illustrated above mean that only the photons in the desired emmission bandpasses of the observed object are contributing to the view. Therefore, red halos around stars will not be present. A more natural and contrasty view is the result. Our Hi Def Filters are made to exacting standards through a coating technology known as Ion Beam Sputtering (IBS). These filters are made on site at the Spectrum Thin Films Facility in NY with state of the art coating chambers. Our filter glass is polished to better than Lambda/8 and coated with our best anti-reflective dielectric material for less than 0.25% reflection. Note the amazing 98%+ transmission percentages illustrated in the light curve profiles at the intended bandpasses of these filters.