1. Telescopes 3 Functions 1. Gather light Size does matter The bigger, the better 2. Resolve detail 3. Magnification Only important for solar system objects

2. Refracting Telescopes Cheap Good for bright objects Basic design

3. Reflecting Telescopes Larger Size = Price Fainter objects

4. Catadioptric Telescopes “Combination” Shorter Reasonable price Common forms – Schmidt-Cassegrain (SCT) Maksutov-Cassegrain (Mak)

5. Telescope Mounts Alt-Az Mounts – Simple – Complex tracking – Fields rotate Equatorial Mounts – Latitude dependent – Tracks easily – No rotation (good for long exposures)

7. 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.

8. 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!

9. Camera Only Constellations Milky Way Meteor showers Aurorae Long time = star trails – No trails: t = 30s – 1 m Hazard: Fogging Hazard: The Moon

11. Prime Focus Moon details (short exposure) Telescopic objects (long exposure) Digital – can “stack” multiple exposures Magnification required for planetary detail Adapter needed – “t-mount”

12. 30 second exp. 1600 ISO 11 exposures Stacked

14. Piggy Back Wide field, faint objects

15. Afocal Steady mount required

16. Video Regular video cams Webcams Security Cams Speciality cameras With t-mount or afocal Software – stack images