Telescopes 3 Functions 1. Gather light Size does matter The bigger, the better 2. Resolve detail 3. Magnification Only important for solar system objects Refracting Telescopes Cheap Good for bright objects Basic design Reflecting Telescopes Larger Size = Price Fainter objects Catadioptric Telescopes Combination Shorter Reasonable price Common forms Schmidt-Cassegrain (SCT) Maksutov-Cassegrain (Mak) Telescope Mounts Alt-Az Mounts Simple Complex tracking Fields rotate Equatorial Mounts Latitude dependent Tracks easily No rotation (good for long exposures) Telescope Details Aperture = size of light gathering opening = D Focal length = distance needed to focus light For the objective (the mirror/body of scope) = f o For the eye piece = f e Magnification = f o /f e Resolution, R = 12.0cm/D (result given in ) For Catadioptric systems, objective is modified by correction plate. Taking Pictures Film 400 speed (ISO) Digital READ THE MANUAL Long exposure times - stars, constellations Short exposure times Moon, planets Brightness control, focus control, contrast control Bracket! Camera Only Constellations Milky Way Meteor showers Aurorae Long time = star trails No trails: t = 30s 1 m Hazard: Fogging Hazard: The Moon Prime Focus Moon details (short exposure) Telescopic objects (long exposure) Digital can stack multiple exposures Magnification required for planetary detail Adapter needed t-mount 30 second exp ISO 11 exposures Stacked Piggy Back Wide field, faint objects Afocal Steady mount required Video Regular video cams Webcams Security Cams Speciality cameras With t-mount or afocal Software stack images