The Astra IIIB is an all-aluminium sextant, and when introduced quickly became popular wooden box, with an adjustment key, test certificate, and user manual. Download Astra iiib sextant manual: ?file=astra+ iiib+sextant+manual Astra III Professional Sextant. This sextant. The Astra IIIB is made by the Changzhou Celestaire Instrument Co. in China, with whom and has instructions for easy installation. We are impressed with the.
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We recommend this instrument because it has more than adequate quality for the job liib is at a reasonable price. A serial number is provided at the time of sextant purchase. Bargains on used instruments still exist. Practice Artificial Horizon This bubble horizon replaces the normal scope on the sextant, and allows you to take a sight without being able to view the horizon.
Sextant Astra IIIB
It has a good sized index mirror, and this index mirror is now silvered on the front face for maximum accuracy. If you are a beginner, the much larger field of view makes it easier to identify the stars through the sextant; and if the boat is moving a lot a sight tube makes it easier to keep the body in view. See discussion of sextant mirror types in the FAQs on our celestial nav home study course.
Aluminum alloy is not new to sextant construction. We are impressed with the degree to which each component of the sextant is tested. It is also of benefit when taking horizontal sextant angles, as you can identify the landmarks and the magnification is not needed. Construction Details The frame is made from lightweight aluminum alloy which resists corrosion.
Even in nautical matters, some things change. Even reading the sextant is easier under low light conditions by having white degree marks against a black background as opposed to scribe marks on a brass arc.
Astra sextants are manufactured in China as a brand name for Celestaire. WinAstro Astro navigation on your PC.
The sextants are assembled and tested in a clean, professional, environment. The Astra IIIB is an all-aluminium sextant, and when introduced quickly became popular due to its low price compared to other models then on the market. It has zero magnification, like a sight scope, and as it is unlit it is not suited for use after twilight.
Its low mwnual, excellent optics, and choice of horizon mirrors and other accessories makes it the perfect selection for beginners. On the other hand, essentially any metal astrz will do the job if it has not been damaged.
WinAstro – Astra Sextants
These days, it is difficult to justify paying iiiib when you can buy this sextant plus two GPS units for the price of most other sextants alone. Yet, we know several professional navigators who prefer the ASTRA IIIB merely because they can leave their expensive models at home without sacrificing noticeable accuracy.
One can always use the price of this new one as a reference for evaluating the price of such an opportunity. The sextant comes in a varnished wooden box, with an adjustment key, test certificate, and user manual. It is made of blackplastic, and astta a matt black interior to minimise refletions.
Astra IIIB sextant
This shape allows more aspect of the mirror to be available for high angle sights. It is also been reviewed as the best source available for how to use metal sextants. Also, and probably more importantly, many people find that the extra weight makes the sextant steadier when taking a sight. There are 4 shades for the index mirror, and 3 for the horizon mirror. It has long been used by many manufacturers for lightweight versions of their heavier brass or asrta sextants in order to reduce arm fatigue and unsteadiness among infrequent users.
Since then its specification has steadily been improved, and it continues to offer good value for money.
An optional additional 7×35 scope is available to enhance sun and moon sights and improve index correction measurements. We also carry a full line of Davis plastic sextants.
You then change the sextant angle to bring the body down to the hairline. An index mirror upgrade kit is available for older models having smaller, round, index mirrors. It comes mounted in a rectangular frame and has instructions for easy installation.
Over 22, sextants of this model have been sold in the US alone in the past 25 years; far more than any other serious sextant.
Its popularity has spread throughout the rest of the world as well, making it the the most recognized and supported sextant worldwide. The sextant is electrically lighted by an LED on the arc and drum. Other differences are that it has an improved handle design, and the light can be dimmed for when viewing faint stars.
When you install the artificial horizon, you calibrate it, and include this offset in your sight corrections. Random units have been tested by us and several professional navigators, with results that rival the most expensive German and Japanese models.
For example, each mirror and shade glass is tested for perfect flatness by the Fresnel diffraction pattern method. Manua recommend the traditional mirror as opposed to so-called “full view” models, and the deluxe version, which has the larger mirrors.
Never before has such a high quality, accurate metal sextant been available at such a low price. The sight scope is 3.