A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2014 Apr 5, 15:45 -0400
I have never handled this instrument either. I trust Nicolas and his methods. Note his careful attention to detail in checking the pentaprism's offset.
I note that the professional Frieberger survey sextant (owned and handled by Anon) has the prism attachment on a post. Perhaps it is so easy to remove that the up mounting is never required.
Anon had no use for the up orientation. Nicolas used it strictly for a one time calibration. Neither used it to measure angles, notwithstanding the catalog blurb.
On 5/04/2014 20:06, Brad Morris wrote: > When attempting angles smaller than 90°, Nicolas states that the prism > does not occupy the entire FOV of the horizon path, and as such, he can > use the sextant in a normal fashion. That is, for small angles, the use > of the pentaprism is avoided entirely That's neat. Both C&P and Freiberger's blurb talk about how measurements are done in both positions though. Not that I've ever seen either instrument - perhaps it's not possible on their version (larger prism?), or perhaps it's not how they intended it to be used. It certainly simplifies things not having to do the transformation for small angles. Luc
View and reply to this message: http://fer3.com/arc/m2.aspx?i=127464