building a dobsonian telescope - using the telescope

There are three parts to the finished telescope:

• Telescope Tube
  - Making the spider
  - Eyepiece Holder
  - Making the Tailgate
• Rocker Box/Ground Board
• Tube Box
• Inserting Mounting Blocks
• Finding Focal Length of Mirror
• Positioning Eyepiece and Spider
• Using the Telescope
  

Using the telescope

Put the eyepiece in brass tubing to give it support. Wrap enough cardboard around the brass tubing to make a snug but flexible fit in the eyepiece holder. Focus the telescope by moving the brass tubing in and out of the eyepiece holder.

If you see the sides of the telescope tube, then the primary mirror needs to be colimated.

To do this put a small sticker in the center of the primary mirror. You can use a template (circle with hole cut out of middle) so you do not touch the mirror surface). Put the primary mirror back and look through the eye piece holder. If the mirrors are lined up properly, the sticker will be in the center of the reflection of the primary mirror. The reflection of your eye should also be in the center of the primary mirror. If the sticker does not appear to be in the middle of the reflection, the primary mirror needs adjusting. You will need a socket wrench and two people to do this. One person looks through the eyepiece holder and the other adjusts the bolts in the tailgate. As the person adjusts the bolts, the other person tells him whether the image is lining up or not. Once the mirrors are lined up, you should only have to do minor adjustments the next time you use the telescope.

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