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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This shape allows more aspect of the mirror to be available for high angle sights.
You then change the sextant angle to bring the body down to the hairline. Over 22, sextants of this model have been sold in ashra US alone in the past 25 years; far more than any other serious sextant.
Also, and probably more importantly, many people find that the extra weight makes the sextant steadier when taking a sight. The Astra IIIB is an all-aluminium sextant, and when introduced quickly became popular due to msnual low price compared to other models then on the market. 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.
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 asttra an advantage. 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. It comes mounted in a rectangular frame and has instructions for easy installation.
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. Upgrades included new box, improved lighting, and larger index mirror. Rubber Eyecap This rubber eyecap can be used with the scope, sight tube or artificial horizon. 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.
Since then its specification has steadily been improved, and it continues to offer good value for money.
Astra IIIB sextant
The index mirror is rectangular in shape and is the same size as used more expensive sextants. 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.
The Astra is dependable and more than accurate enough for the job. This aluminum-alloy instrument manuzl some 2.
Instruction manual for Astra III-B Marine – Search Yale Digital Content
Even in nautical matters, some things change. Sight accuracy is claimed to be about 2′.
This bubble horizon replaces the normal scope on the sextant, and allows you to take a sight without being able to manuzl the horizon. This means the sextant does not have to be held as steady for them. One can iiib use the price of this new one as a reference for evaluating the price of such an opportunity.
An optional additional 7×35 scope is available to enhance sun and moon sights and improve index correction measurements.
Construction Details The frame is made from lightweight aluminum alloy which resists corrosion. The sextant comes in a varnished wooden box, with an adjustment key, test certificate, and user manual.
The Astra optics are excellent and the instrument has a good feel to it. Aluminum alloy is not new to sextant construction.
The sextant is fairly light with its aluminium frame and plastic handle.
The sight scope is 3. Atra discussion of sextant mirror types in the FAQs on our celestial nav home study course. Its light weight and excellent balance makes it a pleasure to hold and makes sights easier to take under dynamic weather and sea conditions. Astra sextants are manufactured in China as a brand name for Celestaire.
Sextant Astra IIIB
Note that aluminum alloy sextants are not unique to this Chinese manufacturer, even the makers of the expensive brass versions offer asfra alloy models, sometimes even more expensive than their brass 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.
When you install the artificial horizon, you calibrate it, and include this offset in your sight corrections.