I recentlr purchased a 50 x 50 mm Hydrogen alpha filter and unlike other filters I have bought, this one was different on each side of the filter. One side was highly reflective wityh a mirror like look , the other side was not. Question, does it matter which side faces which way? Unlike screw in filters, you only have one choice but the 50 50 mm filters can be installed two different ways and there was no indication on the package. Dale
Put the shiny side towards the telescope, to minimize any reflections between the camera and the filter.