For a simple starter, I'm curious what the transparency of pane glass is. Moreover, we have a domed observatory and one of the two shutters (lower) has a common window pane about 3' on a side. In fact, there are three elements of the shutter area; upper, lower, and a wind screen (below the lower shutter). Typically, we do not use the wind screen. When used it can be attached to the lower shutter, and drawn up from a spool on which the screen is wound. In this format, it has the advantage of keeping air from circulating into the dome, and providing air stability. It recently was brought to my attention that maybe the wind screen should be in use because of the stability just mentioned. However, that may not be good if the window transparency is say 70-80%. The CCD camera on the telescope is use for astrometry, so b/w is fine. No need for color photography. However, it may be that the glass might flex when the inside and outside temps are different. Possibly dirt on the window may be a factor. I have do idea yet if this would cause trouble. Comments are welcome any of this?