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Re: Side Error & Index Check
From: Hewitt Schlereth
Date: 2015 Jun 8, 19:37 -0700
From: Hewitt Schlereth
Date: 2015 Jun 8, 19:37 -0700
Bruce, it doesn't sound like you've got very much side error.
My 1992 edition of Bauer's book has a drawing of side error with a star in Chapter 2, on page 53, Fig 2-9. Page 50 describes the adjustment procedure. Read also the last paragraph on page 55.
If you do want to try it with the Astra III B, the the adjustment for side error is done with the little socket wrench. Set the reflected star directly alongside the actual one. Insert the wrench into the socket on the outside rim (East; 3 o'clock) of the horizon mirror frame and turn it gently to move the reflected star onto the real one.
Now recheck index error. If it's more than you can tolerate, use the wrench in the socket on the upper left rim (NNW) of the mirror frame to reduce it. Since the two adjustments affect each other you may have to go back and forth a few times. Patience, pilgrim. Easy does it.
Actually, the greatest risk is dropping the tiny wrench. Don't do this on the edge of a deck over shrubbery, or one with gaps in the flooring. :-)
Hewitt
Hello:
My Astra has always had a very small index error......maybe 1 minute on or off at most . Very stable. Last night I just decided to check the index against a very clear Venus. With about zero angle, when I went to align the images, I found to my great surprise only a partial overlap of the "stars". The index error was about zero so I don't intend to make any adjustment. Bauer calls this "side error" and it would require professional adjustment. I must say that checking the index against a star overlap seems easier than against a fuzzy horizon. Why is it not mentioned more often? Seems basic to me.
Comments appreciated..still learning here.
Best regards
Bruce
