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Bill, 

Use the dark scope ocular lens filter cap on the ocular of the scope. To do this take off the scope rubber eye cup then press fit the dark filter cap on. Set sextant to zero. Now observe Sun for determine index error. If more tha 1' then it is worth using the horizon mirror adjustment tool to take the error out. While you are at it then check side error. I like to leave a little bit of side error in so that the reflected Sun image doesn't get lost behind the direct image.

You may want to select shades with scope off the sextant. Once selected mark the shade combinations with whiteout for future use on a bright Sun. It is also easier to find the Sun in the artificial horizon without the scope on and to then bring the Sun down with index arm. Put the scope back on for the actual observation. Another way is to figure Hc with USNO data and double the value as an artificial horizon preset. Both Suns should then be within the field of view.

Greg Rudzinski

From: Bill Lionheart
Date: 2016 Mar 12, 01:15 -0800

I worry I might make a mistake doing a sun sight and damage my eyes and I have not had anyone carefully explain the best procedure. When I did my RYA Yachtmaser Offshore course(in the 1980s) it was an evening course - so we saw lots of stars!  Here is what I usually do with my Davis.  Set the sextant to zero and put in all the filters.Point it at the sun. If the sun is toodim take out somefilters (but they are different colour so which first?). Bring the sun down to the horizon and maybe remove a another filter from the horizon if the reflected image is too dim.  As the Davis has a "full hirizon" mirror both the horizon and the sun are attenuated.

Is that the right procedure? I have occasionally cautght a glimpse of the sun sneeking around the filters so my technique is still not quite right! Should I do anything different with an artificial horizon?

So I just got a very nice Tamaya MS2L (636) which has a 7x35 monocular. This has, in addition to index and horizon filters, two filters built in to eye pieces for the monocular. One is polarized they other just very dark. How should I use these?

Many thanks

Bill