Blocking out any pinholes should be done on inside coated surface. Blocking can be done with a fine point felt marker, small drop of paint, typing correction fluid etc. It is not necessary to touch-up any small pinholes that do not cause image problems. There is no danger if some pinholes or minor scratches are present, and the touch-up procedure will not lessen the optical performance. All filters are tested for safety before shipment.
Filter consists of two coated layers with coatings protected in center.
Clean same as glass, however, use extra care since the film is more fragile than glass. The two layer design eliminates pinholes and scratches. Clean same as Polymer Plus. When using low magnification the image may appear bright in some telescopes with ND-5 filters. Color or polarizing eyepiece filters can be used in addition if desired.