NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: planned purchase astra IIIB
From: Alexandre Eremenko
Date: 2007 Jan 28, 20:51 -0500
From: Alexandre Eremenko
Date: 2007 Jan 28, 20:51 -0500
On Sun, 28 Jan 2007, coralline algae wrote: > Upon delivery what should I look > for to insure that there are no major > problems with the instrument. Visually inspect all parts to be sure that they are unbrocken, that everything which should move moves smoothly, and what should not move does not move. Try to shake the (clamped) index arm with your hand in both directions. It should not shake. Check and adjust perpendiculatiry of mirrors. Check collimation. (This is not adjustable on Astra! If it is out of collimation, return it). Determine the IC. Then do it again, sextant uspide down Then two more times, sextant horizontal. It should be the same in all positions. Check for backlash. Finally take some sights from a known position and reduce them. Take some star distances. On traditional versus full-view mirrors. I feel that traditional mirrors are better. They are certainly better for all twilight observations. And in the daylight they have no substantial advantages. With a 6-8 scope, the picture you see is practically the same. With the ordinary scope, traditional mirror requires a bit more practice, but I do not thing this justifies a full-vew mirror. Alex. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---