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):||13 June 2009|
|PDF File Size:||15.44 Mb|
|ePub File Size:||14.73 Mb|
|Price:||Free* [*Free Regsitration Required]|
Sight accuracy is claimed to be about 2′. 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.
Slip-on Rubber Eyecup for Scope. Awtra index mirror is rectangular in shape and is the same size as used more expensive sextants.
It has zero magnification, like a sight scope, and as it is unlit it is not suited for use after twilight. Random units have been tested by us and several professional navigators, with results that rival the most expensive German and Japanese models. Since then its specification has steadily been improved, and it continues to offer good value for money.
For example, each mirror and shade glass is tested for perfect flatness by the Fresnel diffraction pattern method.
On the other hand, essentially any metal sextant will do the job if it has not been damaged. See discussion of sextant mirror types in the FAQs on our celestial nav home study course. Rubber Eyecap This rubber eyecap can be used with the scope, sight tube or artificial horizon. 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.
The Astra optics are excellent and the instrument has a good feel to it. You then change the sextant angle to bring the body down to the hairline. 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.
Even in nautical matters, some things change.
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.
The sight scope is 3. 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. This shape allows more aspect of the mirror to be available for high angle sights. The sextant comes with the traditional, all-purpose “4×40” telescope.
Astra IIIB sextant
The sextant comes in a varnished wooden box, with an adjustment key, test certificate, and user manual. Astra sextants are manufactured asttra China as a brand name for Celestaire.
It has a good sized index mirror, and this index mirror is now silvered on the front face for maximum accuracy. Its light weight and excellent balance makes it a pleasure to hold and makes sights easier to take under dynamic mnaual and sea conditions. Its popularity has spread throughout the rest of the world as well, making it the the most recognized and supported sextant worldwide.
The Astra is dependable and more than accurate enough for the job. The sextant is fairly light with its aluminium frame and plastic handle. 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.
It is also been reviewed as the best source available for how to use metal sextants. It is also of benefit when taking horizontal sextant angles, as you can identify the landmarks and the magnification is not needed.
We recommend this instrument because it has more than adequate quality for the job and is at a reasonable price. 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.
Instruction manual for Astra III-B Marine – Search Yale Digital Content
One can always use the price of this new one as a reference for evaluating the price of such asttra opportunity. We recommend the traditional mirror as opposed to so-called “full view” models, and the deluxe version, which has the larger mirrors.
The sextant is electrically lighted by an LED on the arc and drum. Over 22, sextants of this model have been sold in the Manaul alone in the past 25 years; far more than any other serious sextant.
WinAstro Astro navigation on your PC.
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. Please do not be misled by the title. Its low price, excellent optics, and choice of horizon mirrors and other accessories makes it the perfect selection for beginners. An optional additional 7×35 scope is available to enhance sun and moon sights and improve index correction measurements.
It comes mounted in a rectangular frame and has instructions for easy installation. Beschrijving Metalen halfzicht Sextant in traditionele houten kist. Amnual you install the artificial horizon, you calibrate it, and amnual this offset in your sight corrections. Construction Details The frame is made from lightweight aluminum alloy which resists corrosion.
We are impressed with the degree to which each component of the sextant iikb tested. Upgrades included new box, improved lighting, and larger index mirror.