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Sam,

The whole horizon has a very large working field of view. This is advantageous when a fast sight on the Sun becomes necessary such as in rough weather or when the Sun is in and out of the clouds. A real convenience on a small craft. The down side is that checking index error by horizon alignment is made difficult as are horizontal sextant angles. The split mirror is more demanding in that the body needs to be center field. The big advantage of split mirror comes into play when trying to observe dim stars and faint horizons where the extra light from a fully reflective surface can mean the difference between success or failure to observe. When using the whole horizon mirror I prefer a x4 scope or less and with a split mirror a x4 scope or more and especially with the 7x35mm scope. On artificial horizon observations I go with a split mirror and x2 scope or sight tube.

Greg Rudzinski

From: Samuel L
Date: 2015 Nov 20, 05:28 -0800

Greg,

What advantage does a whole horizon mirror have over a split horizon?  Is one more advantageous than the other?

Thanks,

Sam