Fujinon Polaris 10x 70 mm MT-SX Binocular

Right: Fujinon 10x 70 mm MT-SX Binocular (121,697 Bytes).
Click on image to see enlarged view (326,841 bytes)

The magnification and aperture balance along with the good optical design means the 10x 70 mm MT-SX makes good sense for those who do not need to wear spectacles (sunglass or prescription). And so these are a less costly alternative to the 10x 70 FMT-SX for those pursuing astronomy from rural skies where exit pupil is more practical given the eye's ability to fully dark adapt in these areas and where some lack of sharpness of stars nearing the edges of the field of view is acceptable. Larger Comets, immense diffuse emission nebula, and other extended objects appear more distinct in part due to the magnification, but in some measure due to the large 7 mm exit pupil than that of the 16x 70mm model for example. For routine uses we prefer the extra magnification provided by the 16x 50 mm FMT-SX since this also helps to reign in more deep sky objects that tend to be smaller than the five degree area of sky shown by the 10x 70 mm MT-SX. A number of Company Seven's clients and some of our employees have been able to identify the entire Messier Catalog from suburban skies with the 16x 70 mm FMT-SX and it's predecessor the 14x 70 mm FMT-SX. In cases where one prefers to operate hand held or in rare instances where a Comet makes an approach close enough to Earth to appear immense, then the wider and more perfected fields of view provided by the 10x 70 mm MT-SX or possibly the 7x 50 FMT-SX may be more desirable.

The Fujinon company is based in Japan and is a well regarded maker of medical, photographic and sports optics products. Their MT-SX series are their result of years of efforts to perfect a series of binoculars that are suitable for highly demanding marine and terrestrial uses. These systems employ a refined doublet objective lens arrangement feeding substantial optical glass (BaK-4) porro prisms and so light fall off or vignetting are among the most modest in production binoculars. These are matched to a very comfortable eyepiece. Fujinon's multilayer electron beam deposited antireflection coatings assure a high degree of light throughput, and the elimination of ghost images or glare. The result provides an high degree of contrast, clarity and sharpness across most of the eld of view. And these feel reassuringly firm and well balanced in the hand.

The MT-SX series offer a good value overall in terms of performance, reliability, and comfort among all the consumer oriented 70 to 80 mm binoculars made. The 70 mm MT-SX series tend to outperform most others consumer oriented 80 mm binoculars made by in Japan and China, even though the 70 mm MT-SX may cost about the same as these competitors.

All air to glass surfaces of the SX series are E-Beam coated. The color correction of the MT-SX and FMT-SX are quite good too. When looking at a target centered in the field of view: a bright star (Sirius, Vega, etc.) or a black bird on a tree contrasted against a light blue sky, you will not observe any obvious secondary color fringing. The terminator of the Moon for example is sharp, crisp, and three dimensional contrasted against the blackness of space.

The optical performance alone could be considered the critical best feature for a demanding astronomer, and this is not commonly found with most other binoculars anywhere near this cost. Incidentally, we find it more than coincidental that the 70 mm FMT-SX are considered the "poster child" of astronomy binoculars and one was selected by Phil Harrington to grace the cover of his book Touring The Universe Through Binoculars which we also stock. But in addition to the very good optical aspects, there are highly attractive mechanical features:

Left: cover of Phil Harrington's book "Touring the Universe Through Binoculars" (24,583 bytes).
Click on image at left to view enlarged view (116,734 bytes).

• Individual Focus: the user initially sets focus by turning each of the two eyepiece housings clockwise or counterclockwise, and once focus is set for infinity then there is no need to fiddle with it. It is possible to adjust each independently and so if you have normal vision, then you may set "0" on the dial. Or if you have prescription glasses with one eye -1.5 and another +2 then it is a simple matter to dial these in on the eyepiece indicator scales and then make fine adjustments as may be needed. The depth of field of focus is so great with these binoculars, that once focused for infinity one may see details on objects as near as about eighty feet without having to focus again.
  

  Thus individual focus eyepieces and mechanical bridge design are helpful considerations for astronomy and shipboard marine use too where one needs to be able to pull the binocular up the eye and see a target in the distance quickly, and without wondering if an object coming out of the fog is in focus or not. The individual focus arrangement facilitates sealing against water and the elements.
  

  The eye relief (distance from the eyepiece lens to the eye) is 12 mm; adequate for anyone who does not need to wear prescription or sunglasses. The rubber eyecups are slipped onto a threaded metal ring, and this assembly threads over the eyepiece; in time these can be replaced easily since they are threaded in place. Their 7 mm exit pupil make this binocular more practical to use for astronomy than those of similar aperture and with smaller exit pupils for those in the urban where their eyes may dilate to accept a large exiting light cone.
  

  The "M" in the designation indicates this is a Fujinon binocular designed for marine use. The MT-SX meet the US military specifications for water proofness. This rating is a measure of the binoculars' capacity to survive immersion in water at depth for a period of time. Our sense is the binocular will tolerate more shock, vibration and water immersion than the owner will. Furthermore, the metal and alloy materials used in the construction are nonferrous and so the binocular will not distort a magnetic compass.
  

1. The high efficiency of the MT-SX optical design made possible by advanced glass and coatings technologies make up in quality for whatever they may lack in aperture. We often find moderate cost 80 mm models incorporate designs that simply can not transmit as much light as the MT-SX or FMT-SX, often these 80 mm models incorporate a Field Stop (a washer like ring) just behind the 80 mm objective lens to reduce the effective aperture as a means to make the view appear sharper, all while cutting the effective light gathering power and resolution.
   

2. Mechanical durability provides longevity. Given reasonable care, then these individual focus MT-SX can provide a lifetime of good service that is simply no likely to be matched by comparatively priced center focus 80 mm models. Company Seven has never received a new FMT-SX that arrived with quality control defects, or that was shaken out of collimation. While in the case of the less costly 80 mm binoculars for example, the may come out of the box new out of proper collimation to some degree whether immediately obvious or not - this is why we have to check each of these meticulously. And assuming 80 mm binoculars arrive intact, then most must be handled and transported gingerly compared to the 70 mm FMT-SX.

Now we are not saying that the less costly 80 mm models are useless, many 80 mm models coming from Japan, and as China improves from there too, are a fair value for many people. We simply want one to understand the differences in what they are buying when they spend $300 or so less than the FMT-SX to buy an economical 80 mm: most people who spend somewhat more to buy the Fujinon 70 mm FMT-SX are happier, longer.

Baffled and antireflection covered interior construction prevents ghost images and reduces possible effects of glare all accomplished without any loss of contrast or definition. Observations of even the brightest objects (the Moon, etc.) against the background of the night sky show no ghosting or flare.

The Fujinon MT-SX binoculars as distributed by factory authorized retailers in the USA are provided with a slip on rubber eyepiece cover (sometime called a rain guard), slip on objective lens covers, neck strap, padded hard shell carrying case, Fujinon Lifetime Warranty for the mechanical and optical components. Every Fujinon received at Company Seven undergoes a comprehensive testing and approval process, so whatever we deliver will be among the best example that the factory can produce!

Right: A Fujinon 10x 70mm MT-SX with objective caps in place, greets you from within the provided carrying case (51,859 Bytes).
Click on image to see enlarged view (148,543 bytes)

This binocular is among our popular choices for astronomy, and we encourage you to buy one or two guidebooks to help you progress in the hobby. Please refer to our on line section describing some of the most recommended book titles by Company Seven for guides to the Messier Catalog and other objects brought within your grasp by these binoculars.

Below Right: Fujinon 10x 70mm MT-SX binocular (100,741 Bytes).
Incidentally, the MT-SX binocular in this image FAILED Company Seven's inspection process and was returned to the factory - can you find the anomaly?
A few other shops out there claim they check what they sell, yet few return anything to the distributor. Where will you buy your own Fujinon?
Click on image to see enlarged view (224,216 bytes)

10x 70 MT-SX Binocular Specifications

Magnification	10 X
Objective Diameter	70 mm
Twilight Factor †	26.5
Relative Brightness ‡	49
Exit Pupil Diameter	7.0 mm
Eye Relief	12 mm
Closest Focus Distance	Appx. 15 meters (45 ft)
I.P. Span	56 to 74 mm
Apparent Field of View	53°
Actual Field of View	5.3° 91 meters @ 1 km
Weight	2,029 g. (71.6 oz.)
Height (Eyecups extended)	276 mm (10-7/8 inches)
Width (typical with IPD at 62mm)	222 mm (8.7 inches)
Width (maximum)	212 mm (10-7/8 inches)
Depth (at Prism Housing)	70 mm (2-½ inches)

† Twilight Factor (sometimes termed Relative Brightness) is a mathematical product of a formula. This formula however, does not factor differences of quality. For example two 7x 50 binoculars of vastly differing qualities will produce the same value by using this formula, and so this should only be used to compare binoculars of similar quality (i.e. a Fujinon 7x 50 FMT vs. Fujinon 10x 70 SMT-SX).

Twilight Factor = Square Root of (Diameter of Objective Lens x Magnification)

† Relative Brightness (or Relative Light Efficiency) pertains the the efficiency of the optical system in terms of throughput of light. This is measured by sensitive equipment and can help one to determine quality differences between models.

* Specifications are subject to change without notice.