Does anyone know how to introduce a red filter between these two items. Does the process require a method to make the front lens ring of the PT-015 watertight to the Inon lens or the filter?. As you know there are four holes in the front of the PT-015 red lens ring. To state the question another way, must these holes be sealed? ie is the water allowed to enter between the PT-015 and any attachments I may add? Ken