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Frank,

I didn't realize that my Davis 25 had a shade problem until you posted about your experience with someone else's 25. I acquired my 25 in 2021 and when I first used it I thought the image of the sun through the index mirror was a bit bright. I taped an additional shade ( sometimes two), made from disposable dark glasses I was given after a dilated eye exam, on the front side of the forward-most shade and have left it in place ever since. Early on I did a some Noon Sights for Latitude and a few other things and more recently I have done some Lunars. I'm careful to not leave my sextant out in the sunligh for any length of time. A year ago, a friend gave me his Davis 15 sextant when he realized that he was never going to be able to put in the time to learn CN. He purchased it about 2005. I could tell that it had never been out of its box. So I figured that I was in a unique position to compare a relatively new 25 with an older 15. There is definitely a difference. Through each horizon stack, I viewed the sun without any other things in the light path. The sun's image through the shade stack (3 shades) of the 25 was uncomfortably bright with a lot of glare. In addition to the sun being seen through the shades, there were 3-4 other Bris-like images of the sun present, even though the shade stacks of both sextants seemed to be similar. Through the 15's shade stack, the sun's image was very easy to view, with only one image and no glare. There was quite a difference between the 2 sextants. I tried to take pictures with my iPhone, but couldn't capture very well what I was seeing. I have included 2 picutres, one through the shade stack of the 15 and 25 (multiple images of the sun). The phone's camera seemed to be focusing on the closest shade rather than on the sun's image through the shades. I have left out some details of what I did to make this comparison. I was careful when viewing the su because my father was on ophthalmologist and I knew to be cautious.

As an additional test, I compared a single blue shades from each sextant by looking at a picture of friends that was lying on my kitchen counter. The picture scene was not particularly well lit, but I could recognize faces through the 25 shade, but not through the 15 shade. Just looking at the blue shade of each, the 15's did seem a bit darker.

Who would have guessed?

Homer S.

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