| Consists of two 30% transmission polarizing filters mounted in an adapter tube that fits into a 1.25" star diagonal. One filter is fixed at the bottom of the #905 tube and the other is mounted within the tube and is free to rotate. A 1.25” eyepiece slips into the top of the #905 tube and is held in place by a thumbscrew. The light transmission through the filter is varied over a 5% to 25% range by moving the lever shown at side of tube. The lever rotates the internal filter in relation to the fixed filter and eyepiece. The lever also acts as a thumbscrew to lock the orientation of the internal filter in place at any desired light transmission. The filters cannot be removed and used individually. The #905 tube holds the eyepiece 1-7/8” above the star diagonal or focuser. Accordingly, it is designed for use in the star diagonals of Schmidt- and Maksutov-Cassegrain scopes that have a long back focus. The #905 will not work with reflectors and refractors as these scopes typically do not have enough focuser in-travel available to let the eyepiece reach focus. |