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On 21/03/2022 17:00, Dale Lichtblau wrote:
> I have
> determined that the two arms that attach the bubble and the regular
> telescope to the frame are of different lengths ~3mm. Pictures attached.
> C&P asked me just to send it to the Kompass Haus in Bremerhaven for
> repair. (I love these German professionals.)

I also have a C&P with bubble attachment. I hadn't noticed before but
indeed the optical axis of the bubble chamber is about 3mm further away
from the frame compared to the telescope.

There's a clear view of the horizon mirror when sighting through the
bubble horizon, so it doesn't matter. The optical axis just needs to be
parallel to the frame. It doesn't need to be e.g. centered on the
horizon mirror.

(If you look at the sextant, there's a small angle bracket to which the
telescope is mounted. It's attached to the sextant by two screws. These
screws can be tuned to make sure the optical axis is parallel to the
frame. I've not dared to touch them myself, yet.)

Perhaps the bubble horizon and the sextant were not designed at the same
time, or even at the same company. I can't think of a reason to design
the bubble horizon in such a way that it's 3mm to the left. It may have
been designed 75 years ago for a different sextant.


I'll probably write a little manual for how to get good results with the
bubble horizon at some point. It was very frustrating at first.

Luc

   

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