This Baader narrowband 8.5nm O-III filter is for imaging deep sky objects that emit in O-III and is suitable for use with large format/full frame imaging cameras.
Each individual filter is optically fine-polished to 1/4 wave and are hard coated. All Baader filters sport scratch resistant hard coatings which can be cleaned repeatedly throughout their entire lifetime as many times as needed – preferably with Baader Optical Wonder cleaning fluid.
Baader filters are individually made and not cut out of a larger plate-glass “master” (which is a typical manufacturing process for economy filters) as cut-out filters exhibit micro-cracks around all edges and capillary action between glass and coating layers will lead to premature ageing due to moisture deposition. All Baader filters have individual coating sealed edges, impermeable against ageing because the penetration of moisture is impossible.
Baader filters are continually tested to comply with MIL-specifications. One common test process is to boil the test specimen for one hour in salt water. Baader filters remained completely intact as opposed to filters drilled out of large glass plates.
This item is brand new, supplied in its original, unopened packaging.