Spider and Front End

This image gives you a pretty good overall view of the front end of this scope.  With the direct sunlight on the spider, you can see the front wires (there are back wires as well, triangulated to give good rigidity to the spider as well as providing fore and aft adjustment, but you can't seem them inside the dark tube).  You can also see into the diagonal mount (made of lightweight PVC pipe parts), and see the primary mirror down the tube.  On the outside, the focuser (the one major part I bought instead of making) and the Rigel QuickFinder are visible.

You can readily see the out of round tube, due in part to the manufacturing methods used to produce a tube that could be shipped and sold with the seam open, then closed by the end user, and in part to the tension in the spider wires.  Though it looks pretty ugly, it doesn't intrude detectably into the light path, so has no effect on the images.  Still, it detracts from the appearance of the scope, and I intend to make an end ring to bring it back into round.  That will, of course, require a major front end recollimation, but that's pretty easy with the tensioning system I have.

You can also see the inner ends of the three sheet metal screws that hold the left side tensioner to the tube -- again, they don't intrude into the light path, but next time I'm going to have the front end apart anyway, I plan to check if I can get screws about 1/4" shorter to reduce their contribution to diffraction.  If not, I'll probably try to cover them on the inside with black felt or velvet.

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If you have comments or suggestions, email me at silent1@ix.netcom.com