 |
These
photos show a commercial finder eyepiece with cross hairs.
There is a threaded sleeve which has the cross hair wires soldered in place (left object in left photo). When mated with the eyepiece, you screw in the sleeve until the cross hairs are in focus. So to add cross hairs to an eyepiece you have to solve two basic problems. (1) Find a suitable material for the cross hairs and (2) Find some way to hold them at the correct vertical position in front of the eyepiece lens so that they are in focus. |
 |
This
is how I solved Problem Number 1. For the cross hair material I use
a single strand of the nylon material used in making nylon binding cord.
You can separate the cord into single strands with a razor blade or hobby knife. Also use the hobby knife to slice some thin strips of tape from the standard roll. Next gather up considerable patience and ingenuity and attack Problem Number 2. |
 |
For
ingenuity, I gathered several small washers from a junk box. Then
I made washer sandwiches until I found a thickness that would hold the
tiny strands at the correct vertical position.
This required many unsuccessful attempts. Once a correct combination of washers was found, I taped the two strands at right (well almost) angles across the washer opening to make the cross hair. This taping task also required considerable patience. My most successful technique was to use two hobby knife blades to position and move the small pieces of tape and nylon strands. I finally declared victory after about four failed attempts. Finally tape the entire assembly into the eyepiece. Yes, it really does work. At least good enough to quickly see the movement of the drift star. At 1,000 powr, the star image is not usuable for
any other purpose.
|
|
|
 |