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?

1. Tap water2. Washing-up liquid3. 5 Litres of distilled water4. Cotton wool – preferably surgical5. Vessel large enough to take the mirror6. About an hour of your time

Removing the mirrorLay the telescope on a flat surface.

Removing the mirrorLocate the tube fixing screws – note an alignment mark for replacing the cell

Alignment mark

Removing the mirrorGently withdraw the mirror cell

Removing the mirror

Removing the mirrorLocate the mirror fixing brackets

Removing the mirrorUnscrew and remove the brackets

Removing the mirrorCarefully remove the mirror from its cell

Washing the mirrorFill the trough with tap water

Washing the mirrorPut in a sparing amount of washing-up liquid

Washing the mirrorSwish the water around to get an even spread of soap

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

Washing the mirrorThe mirror should be about 2cm below the surface

Washing the mirrorGently swish the water across the water for about 5 mins

Washing the mirrorUse only the weight of a swab of cotton wool to remove stubborn marks

Washing the mirrorRemove the mirror while getting ready to rinse it

Rinsing the mirror

Rinsing the mirrorUse 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

Rinsing the mirrorAfter rinse and drying the trough, empty the container into it

Rinsing the mirrorReplace the mirror and swish the water over it

Drying the mirror

Drying the mirrorStand the mirror on its end on a towel and let it dry naturally

Collimation – Newtonian Telescopes

Collimation – Newtonian Telescopes

This guide describes:

• Technique for visual use only

• Using a laser collimator

Why collimate?

By aligning optics as well as possible improves the performance of the telescope. Newtonians notoriously fall out of collimation very often.

Collimation – Newtonian Telescopes

Collimation – Newtonian TelescopesBefore starting…

MAKE SURE THE OPTICAL TUBE IS HORIZONTAL

You don’t want to drop anything onto the primary mirror!

Collimation – Newtonian TelescopesWhat needs adjustment?

1) Radial position of the secondary mirror

Collimation – Newtonian TelescopesSecondary sighting tool

A Kodak 35mm film pot is ideal for this purpose!

Collimation – Newtonian TelescopesWhat 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.

Collimation – Newtonian TelescopesWhat needs adjustment?

• Collimation of the secondary

Centre spot on primary is required

Collimation – Newtonian TelescopesWhat needs adjustment?

• Collimation of the secondary

Collimation – Newtonian TelescopesWhat needs adjustment?

• Collimation of the secondary

Collimation – Newtonian TelescopesWhat needs adjustment?

• Introducing the Laser Collimator

Collimation – Newtonian TelescopesWhat needs adjustment?

• Collimation of the secondary

Collimation – Newtonian TelescopesWhat needs adjustment?

• Collimation of the secondary

Collimation – Newtonian TelescopesWhat needs adjustment?

• Collimation of the secondary

Collimation – Newtonian TelescopesWhat needs adjustment?

• Collimation of the secondary

Collimation – Newtonian TelescopesWhat needs adjustment?

• Collimation of the primary mirror

Collimation – Newtonian TelescopesWhat needs adjustment?

• Collimation of the primary mirror

Adjustment screws

Locking screws

Collimation – Newtonian TelescopesWhat needs adjustment?

• Collimation of the primary mirror

Collimation – Newtonian TelescopesIn 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

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.

Digital Setting CirclesThe Altitude Encoder

Digital Setting CirclesThe Azimuth Encoder

Digital Setting CirclesThe Interface Box

The Dave Ek Digital Setting Circles printed circuit board - $24.00

Digital Setting CirclesThe Interface Box

Digital Setting CirclesThe Interface Box

Digital Setting CirclesThe Interface Box

Digital Setting CirclesThe Interface Box

Digital Setting CirclesThe Interface Box connected to a PC serial port

Digital Setting CirclesThe Interface Box connected to a Bluetooth serial adapter

Digital Setting CirclesSoftware – Android Smart Phone

• Sky Safari Plus (cost ~£8.00)

• Massive database of different types of objects

• Contains 2.5 million stars – excellent for zooming in to see the star filed as seen in the eyepiece – makes spotting the object more easy.

• Easy telescope control using

Digital Setting CirclesSoftware – PC Planetarium

• The software which use ASCOM drivers will work

• Sky Map Pro does

Digital Setting Circles

Digital Setting Circles

The End