STAR DIAGONAL CONSTRUCTION
If you want to be able to use your new telescope for watching sailboats in the bay, or search the woods for various birds for your bird watching hobby, you will need a "star diagonal" to form an upright image.
The star diagonal is a bit tricky to make, as you have to make a precision cut, and usually have to file the surface to get a flat surface. If you would like to try for one of these, however, the directions for construction are here!
You will need:
*1 - 2" x 1.5" high quality front surface mirror (the quality will affect performance)
1 - 1" PVC "T" joint
Black, electrical tape (more flexible and tougher than masking tape)
You will need to remove about 1 1/2" of the PVC telescope tube if you want to use the Star Diagonal. Do this BEFORE you assemble your telescope.
Use a glass cutter to cut the mirror...if the ends get nicked slightly, it won't matter. All edges will be taped, anyway.
Hold the joint in a strong vise, and mark your cut with pencil. If you have your lighting just right, you will see a sheen on the cutting line, as the light naturally follows the angle. Cut off one arm of the PVC "T" joint at a 45-degree angle (this is the tricky part). This will leave you with a small tube with a 45-degree angled edge, and an elbow with an open 45-degree hole on the outside of the elbow bend. After cutting, if the surface isn't flat (it won't be...[sigh]), use a flat file to smooth and even the edges. (This may take some time....)
Using electrical tape, tape the mirror to the outside of the diagonal cut, making sure that the mirror face (aluminized surface) covers all of the hole without gaps, and that the back of the mirror (the clear, unaluminized surface) is the one facing outward and being taped. If you get this backwards, all you'll get is double images instead of a clear, upright image. Use as much tape as is needed to cover the edges of the glass, and to secure it to the joint. You aren't going for "pretty" here...you are aiming for functionality.
* C & H Sales--mirror # OL 7806 (1/8" inch X 7 3/4")
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