NavList:

Homer S., you wrote:
" when shooting a lunar, I view the sun through the index mirror with all 4 shades deployed and I have an additional shade made from disposable dark glasses I was given after a dilated eye exam that is double-stick taped to the front of the shade stack. I also was wearing sunglasses (medium tinted I would say). With these 6 shades in place, the disc of the sun was very sharp and comfortable to look at. I don't deploy any of the horizon shades so as to get the brightest image of the moon (sun glasses on still). To look at the sun through the horizon mirror I deploy the 3 shades in front of the horizon mirror in addition to the taped-on shade described previously and my sun glasses. The sun was quite bright "

Aha! I did not realize in our earlier discussions that you had shade trouble. I have discovered, just within the past year, that some relatively new Davis sextants have poor shades (also some older Davis sextants may suffer from a similar issue from "faded" shades). The shades are not dark enough for ordinary Sun sights, and of course that means they're also not dark enough for Sun-Moon lunars. On at least one sextant I looked at, helping a student frustrated by his inability to get good sights, the shades were quite uncomfortable and possibly dangerous. After seeing it myself, it was no mystery that his sights were bad. He did not realize that what he was seeing was not normal. I would not have guessed the problem was so bad without looking through his sextant myself!

I would suggest you consider trading out of your current Davis sextant. They're not hard to sell, but you have to decide whether you would want to pass along a sextant with poor shades to some unsuspecting buyer... That's a tough call. And there's always the possibility that some replacement Davis sextant that you might buy later would also have poor shades! Alternatively, maybe it's time to upgrade to a low-end metal sextant.

With three (out of four) shades in the light path in front of the index mirror of a standard Davis Mk 15 or 25 sextant, the Sun should appear as a dull disk --easy to look at, not the slightest glare or viewing discomfort, and with crisp, sharp edges. If you (anyone reading this) don't find that this is the case, you may have bad shades on your sextant. Note that three shades (in some order) are typically enough to properly block the Sun's light, however if you need all four, that's ok. You have more options when three are sufficient, but the sextant is still functional if it takes all four.

Frank Reed

PS: You had written your comments on sextant shades in a thread about lunars. Normally I would leave this reply under that heading, but this issue seems important enough for a separate subject.