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What to do to a Dob

What to do to a Dob. Presentation by Keith Rickard 27 September 2012. Cleaning the mirror. Don’t!. Cleaning the mirror. Yuk!. Cleaning the mirror. What do you need?. Tap water Washing-up liquid 5 Litres of distilled water Cotton wool – preferably surgical

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What to do to a Dob

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  1. What to do to a Dob Presentation by Keith Rickard 27 September 2012

  2. Cleaning the mirror Don’t!

  3. Cleaning the mirror Yuk!

  4. Cleaning the mirror What do you need? • Tap water • Washing-up liquid • 5 Litres of distilled water • Cotton wool – preferably surgical • Vessel large enough to take the mirror • About an hour of your time

  5. Removing the mirror Lay the telescope on a flat surface.

  6. Removing the mirror Locate the tube fixing screws – note an alignment mark for replacing the cell Alignment mark

  7. Removing the mirror Gently withdraw the mirror cell

  8. Removing the mirror

  9. Removing the mirror Locate the mirror fixing brackets

  10. Removing the mirror Unscrew and remove the brackets

  11. Removing the mirror Carefully remove the mirror from its cell

  12. Washing the mirror Fill the trough with tap water

  13. Washing the mirror Put in a sparing amount of washing-up liquid

  14. Washing the mirror Swish the water around to get an even spread of soap

  15. Washing the mirror Gently place the mirror in the water and leave to soak for about 15 mins

  16. Washing the mirror The mirror should be about 2cm below the surface

  17. Washing the mirror Gently swish the water across the water for about 5 mins

  18. Washing the mirror Use only the weight of a swab of cotton wool to remove stubborn marks

  19. Washing the mirror Remove the mirror while getting ready to rinse it

  20. Rinsing the mirror

  21. Rinsing the mirror Use distilled / de-ionised water. This 5L container cost £3.99. Using this water will mean no marks will be left on the surface of the mirror when it is left to dry

  22. Rinsing the mirror After rinse and drying the trough, empty the container into it

  23. Rinsing the mirror Replace the mirror and swish the water over it

  24. Drying the mirror

  25. Drying the mirror Stand the mirror on its end on a towel and let it dry naturally

  26. Collimation – Newtonian Telescopes

  27. Collimation – Newtonian Telescopes Why collimate? By aligning optics as well as possible improves the performance of the telescope. Newtonians notoriously fall out of collimation very often. • This guide describes: • Technique for visual use only • Using a laser collimator

  28. Collimation – Newtonian Telescopes

  29. Collimation – Newtonian Telescopes Before starting… MAKE SURE THE OPTICAL TUBE IS HORIZONTAL You don’t want to drop anything onto the primary mirror!

  30. Collimation – Newtonian Telescopes What needs adjustment? 1) Radial position of the secondary mirror

  31. Collimation – Newtonian Telescopes Secondary sighting tool A Kodak 35mm film pot is ideal for this purpose!

  32. Collimation – Newtonian Telescopes What needs adjustment? • Insertion of the secondary mirror • Orientation of the secondary mirror Left image shows an insertion and orientation adjustment is required. Right image shows the correct position.

  33. Collimation – Newtonian Telescopes What needs adjustment? • Collimation of the secondary Centre spot on primary is required

  34. Collimation – Newtonian Telescopes What needs adjustment? • Collimation of the secondary

  35. Collimation – Newtonian Telescopes What needs adjustment? • Collimation of the secondary

  36. Collimation – Newtonian Telescopes What needs adjustment? • Introducing the Laser Collimator

  37. Collimation – Newtonian Telescopes What needs adjustment? • Collimation of the secondary

  38. Collimation – Newtonian Telescopes What needs adjustment? • Collimation of the secondary

  39. Collimation – Newtonian Telescopes What needs adjustment? • Collimation of the secondary

  40. Collimation – Newtonian Telescopes What needs adjustment? • Collimation of the secondary

  41. Collimation – Newtonian Telescopes What needs adjustment? • Collimation of the primary mirror

  42. Collimation – Newtonian Telescopes What needs adjustment? • Collimation of the primary mirror Adjustment screws Locking screws

  43. Collimation – Newtonian Telescopes What needs adjustment? • Collimation of the primary mirror

  44. Collimation – Newtonian Telescopes In summary: • Generally, only the use of the laser collimator is required • That means collimating the secondary & primary mirrors only • Generally, I find the secondary needs most attention • The process takes 1 -2 minutes

  45. Digital Setting Circles • They aid rapid pointing of the telescope and to allow the user know where the telescope is pointing • This set-up is a Push-To arrangement • Encoders are placed on each axis • Encoders are connected an interface box • The interface box is then connected to a computer • Software on the computer, say a planetarium program, gives the user access to a database of objects to find, etc.

  46. Digital Setting Circles The Altitude Encoder

  47. Digital Setting Circles The Azimuth Encoder

  48. Digital Setting Circles The Interface Box The Dave Ek Digital Setting Circles printed circuit board - $24.00

  49. Digital Setting Circles The Interface Box

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