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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Yet, we asra several professional navigators who prefer the ASTRA IIIB merely because they can leave their expensive models at home without sacrificing noticeable accuracy.

WinAstro Astro navigation on your PC. Practice Ashra Horizon This bubble manuao replaces the normal scope on the sextant, and allows you to take a sight without being able to view the horizon.

In use, you hold the sextant so that the horizon hairline on the right side of the scope lines up with the bubble on the left. Whilst the magnification obtained through having a scope instead of a plain sight tube can make your sights more accurate, there are times when a plain sight tube is an advantage.

The sight scope is 3. It has a good sized index mirror, and manuao index mirror is now silvered on the front face for maximum accuracy.

Sight Tube Whilst the magnification obtained through having a scope instead of a plain sight tube can make your sights more accurate, there are times when a plain sight tube is an advantage. On the other hand, essentially any metal sextant will do the job if it has not been damaged.

Astra IIIB sextant

This aluminum-alloy instrument at some 2. These days, it is difficult to justify paying more when you can buy this sextant plus two GPS units for the price of most other sextants alone. They offer good value for money metal sextants – not as good as Freiberger and other high end sextants, but considerably more accurate than plastic ones.


Aluminum alloy is not new to sextant construction. It has long been used by many manufacturers for lightweight versions of their heavier brass or bronze sextants in order to reduce arm fatigue and unsteadiness among infrequent users. Never before has such a high quality, accurate metal sextant been available at such a low price.

An index mirror upgrade kit is available for older models having smaller, round, index mirrors.

Astra IIIB Sextant

Since then its specification has steadily been improved, and it continues to offer good value for money. It is also of benefit when taking horizontal sextant angles, as you can identify the landmarks and the magnification is not needed. The sextant is electrically lighted by an LED on the arc and mqnual.

Note that aluminum alloy sextants are not unique to this Chinese manufacturer, even the makers of the expensive brass versions offer aluminum alloy models, sometimes even more expensive than their brass models.

Slip-on Rubber Eyecup for Scope. Other differences are that it has an improved handle design, and the light can be dimmed for when viewing faint stars. Random units have been tested by us and several professional navigators, with results that rival the most expensive German and Japanese models.

It is also been reviewed as the best source available for how to use metal sextants. 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.

Construction Details The frame is made from lightweight aluminum alloy which resists corrosion.


It comes mounted in a rectangular frame and has instructions for easy installation. 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. Astra sextants are manufactured in China as a brand name for Celestaire.

We recommend the traditional mirror as opposed to so-called “full view” models, and the deluxe version, which has the larger mirrors.

Sextant Astra IIIB

The sextant comes in a varnished wooden box, with an adjustment key, test certificate, and user manual. The sextants are assembled and tested in a clean, professional, environment. Its popularity has spread throughout the rest of the world as well, making it the the most recognized and supported sextant worldwide.

For example, each mirror and shade glass is tested for perfect flatness by the Fresnel diffraction pattern method.

This means the sextant does not have to be held as steady for them. Even in nautical matters, some things change.

Rubber Eyecap This rubber eyecap can be used with the scope, sight tube or artificial horizon. When you install the artificial horizon, you mnual it, and include this offset in your sight corrections. An optional additional 7×35 scope is available to enhance sun and moon sights and improve index correction measurements. The Astra optics are excellent and the instrument has a good feel to it.

The Astra is dependable and more than accurate enough for the job. It has zero magnification, like a sight scope, and as it is unlit it is not iuib for use after twilight. Beschrijving Metalen halfzicht Sextant in traditionele houten kist.