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Re: Mike's Lunars
From: Mike Hannibal
Date: 2005 Dec 14, 09:14 +1100
From: Mike Hannibal
Date: 2005 Dec 14, 09:14 +1100
Frank and Bill,
Thanks for your supportive comments. I think that the key improvement here is taking Bill's advice and utilising shades for the sights. I have a polariser on both the index and the horizon glasses. I spent some time adjusting these so that I got a useful balance of light from Mars and the moon - both quite dim but with contrast between. Interesting challenge not to "lose" Mars as it came across the face of the moon. I did not employ a "set and wait" strategy - too complex for me. I find that I work best by moving reasonably quickly. Bring the bodies together confirm and take the reading. The slowest part is tracking the two bodies together the first time. I have done a series of Lunars at 70 d separation and getting them together the first time was a challenge.
The sextant is interesting and a total indulgence. When I decided to buy a sextant my nearest and dearest said "you will only do this once so buy a good one". So I bo! ught a C&P Horizon Ultra with some modifications made at my request. The most important one for me is that it has the "Polaris" style horizon glass. This horizon glass has both sides clear and a centre vertical strip half silvered like a whole horizon mirror. It is brilliant to work with. The scope is a 4x40. the only thing I am not happy about with this sextant is that the scope is prone to flare from stray light. The black painting within the scope and around the front element is not a matte paint and is prone to reflect stray light. I have complained to C&P but they aren't terribly responsive. They replaced the index mirror with one that has blackened edges and that has improved matters but the scope remains sub-standard.
Frank I look forward to trying some Sun-Moon lunars I haven't done any yet. I'll report back.
Long response.
Kind regards
Mike
Frank Reed <FrankReedCT@AOL.COM> wrote:
Thanks for your supportive comments. I think that the key improvement here is taking Bill's advice and utilising shades for the sights. I have a polariser on both the index and the horizon glasses. I spent some time adjusting these so that I got a useful balance of light from Mars and the moon - both quite dim but with contrast between. Interesting challenge not to "lose" Mars as it came across the face of the moon. I did not employ a "set and wait" strategy - too complex for me. I find that I work best by moving reasonably quickly. Bring the bodies together confirm and take the reading. The slowest part is tracking the two bodies together the first time. I have done a series of Lunars at 70 d separation and getting them together the first time was a challenge.
The sextant is interesting and a total indulgence. When I decided to buy a sextant my nearest and dearest said "you will only do this once so buy a good one". So I bo! ught a C&P Horizon Ultra with some modifications made at my request. The most important one for me is that it has the "Polaris" style horizon glass. This horizon glass has both sides clear and a centre vertical strip half silvered like a whole horizon mirror. It is brilliant to work with. The scope is a 4x40. the only thing I am not happy about with this sextant is that the scope is prone to flare from stray light. The black painting within the scope and around the front element is not a matte paint and is prone to reflect stray light. I have complained to C&P but they aren't terribly responsive. They replaced the index mirror with one that has blackened edges and that has improved matters but the scope remains sub-standard.
Frank I look forward to trying some Sun-Moon lunars I haven't done any yet. I'll report back.
Long response.
Kind regards
Mike
Frank Reed <FrankReedCT@AOL.COM> wrote:
Mike Hannibal wrote:
"This is a much narrower spread I think than the last lot."
It's also about as close to perfection as I think you could expect! Can you
tell us what type of sextant you're using? What's the magnification of your
sextant's telescope? Was there anything you did differently this time around
that might have removed some of the spread in your previous observations?
Have you tried any Sun-Moon lunars yet? In a week or so, you'll be able to
do those in the morning hours for a few days.
-FER
42.0N 87.7W, or 41.4N 72.1W.
www.HistoricalAtlas.com/lunars
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