TeleGizmos 365 Series Cover for 16"-18" Dobsonian for Vertical Park Position - T34D Alt-Azimuth and Equatorial Mounts which means you use the

which means you use the telescope as a photographic lens—a very big photographic lens

and are parfocal

Field Stop Diameter:           3

even for one person

TeleGizmos 365 Series Cover for 16"-18" Dobsonian for Vertical Park Position - T34D Alt-Azimuth and Equatorial Mounts which means you use theTeleGizmos 365 Series Cover for 16" 18" Dobsonian Telescopes for Vertical Park Position This cover is from the TeleGizmos 365 Series of heavy duty environment protection covers. This TeleGizmos Cover will fit 16" 18" Dobsonian scopes for Vertical Park Position. The cover has a 115" circumference and 90" height. May fit other telescopes; check your dimensions of your scope set up to be sure. NOTE: The photograph shows a generic 365 Series SCT cover