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.
|Published (Last):||12 August 2017|
|PDF File Size:||8.65 Mb|
|ePub File Size:||1.70 Mb|
|Price:||Free* [*Free Regsitration Required]|
The Astra is dependable and more than accurate enough for the job. Astra sextants are manufactured in China as a brand name for Celestaire. 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.
It is also of benefit when taking horizontal sextant angles, as you can identify the landmarks and the magnification is not needed.
Sextant Astra IIIB
The sextant is fairly light with its aluminium frame and plastic handle. 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. Its low price, excellent optics, and choice of horizon mirrors and other accessories makes it the perfect selection for beginners.
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.
We are impressed with the degree to which each component of the sextant is tested. It can take the optional rubber eye cap.
Sextant : Astra IIIB sextant
You then change the sextant angle to bring the body down to the hairline. Other differences are that mqnual has an improved handle design, and the light can be dimmed for when viewing faint stars. The sight scope is 3. We recommend this instrument because it has more than adequate quality for the job and is at a reasonable price.
See discussion of sextant mirror types in the FAQs on our celestial nav home study course.
Astra IIIB sextant
An optional additional 7×35 scope is available to enhance sun and moon sights and improve index correction measurements. An index mirror upgrade kit is available for older models having smaller, round, index mirrors. It is made of blackplastic, and has a matt black interior to minimise refletions.
Sight accuracy is janual to be about 2′. It is also been reviewed as the best source available for how to use metal sextants. It has zero magnification, like a sight scope, and as it is unlit it is not suited for use after twilight. 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. Note that aluminum alloy sextants are not unique to this Atra manufacturer, even the makers of the expensive brass versions offer aluminum alloy models, sometimes even more expensive than their brass models.
Its light weight and excellent balance makes it a pleasure to hold and makes sights easier to take under dynamic weather and sea conditions.
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.
For example, each mirror and shade glass is tested for perfect flatness by the Fresnel diffraction pattern method. 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.
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.
The sextant comes in a astrz wooden box, with an adjustment key, test certificate, and user manual. A serial number is provided at the time of sextant purchase.
The sextant comes with the traditional, all-purpose “4×40” telescope. Aluminum alloy iiibb not new to sextant construction.
Random units have been tested by us and several professional navigators, with results that rival the most expensive German and Japanese models. 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.
Even in nautical matters, some things change. On the other hand, essentially any metal sextant will do the job if it has not been damaged.
The sextants are assembled and tested in a clean, professional, environment. 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.
Bargains on used instruments still exist. We recommend the traditional mirror as opposed to so-called “full view” models, and the deluxe version, which has the larger mirrors. The index mirror is rectangular in shape and is the same size as used more expensive sextants.
The Astra optics are excellent and the instrument has a good feel to it. Upgrades included new box, improved lighting, and larger index mirror.
Astra IIIB Sextant
Never before has such a high quality, accurate metal sextant been available at such a low price. 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.
Since then its specification has steadily been improved, and it continues to offer good value for money. This means the sextant does not have to be held as steady for them.
We also carry a full line of Davis plastic sextants. 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. Construction Details The frame is made from lightweight aluminum alloy which resists corrosion. The ebook must be read from a Windows PC. Slip-on Rubber Eyecup for Scope. The sextant is electrically lighted by an LED on the arc and drum.
One can always use the price of this new one as a reference for evaluating the price of such an opportunity. 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.
WinAstro Astro navigation on your PC.