Nikon WX 10x50 IF review

Nikon has considered the new telescope for a long time. The picture shows the 2010 prototype

. What is the result? Nikon has brought WX 7x50 and WX 10x50 two telescopes. From the point of view of the parameters, the most common place of the two mirrors is the name. In terms of field of view, the two mirrors are 10.7 degrees and 9 degrees respectively, which is also the best part of these two mirrors. In order to compare how wide the field of view is, you need to know that the widest 7x50 and 10x50 are only 7.5 degrees and 6.5 degrees. In addition, Nikon also ensures that under such a huge field of view, the edges must be corrected well, and the exit pupil distance must be comfortable enough.

So there are no shortcomings in these two models? I have already said, volume/weight/cost. The final mass-produced product of these two mirrors weighs 2.5 kg and the length is 30 cm. The price is even higher, reaching 4W. It’s even more expensive if you choose the Centennial Edition.

The left side is the prototype of the mass production version,On the right is the 2015 version of the prototype.

design

It would be great to evaluate such a mirror, but I think it is necessary to introduce the optical design of this mirror.

Modern telescope objectives are basically universal, and slightly better grades may use two-piece gap-separated ED (low dispersion glass). Nikon's design is one step closer, using three pieces, one of which is ED glass.

Side profile view of Nikon WX

From the above figure, you can basically see the lens layout of Nikon WX. If you look closely, you might think that objective lens does not have only two elements? In fact, the first piece may be double-adhesive, and then you can see Abbe prism, Abbe prism is a total reflection prism, this configuration can ensure the brightness of the picture, the contrast (contrast) is good enough.

Behind the prism you can see two plan lenses, which are mainly responsible for compensating the curvature of the field of view from the center to the edge of the picture. On the back is a huge eyepiece group, which looks like 6 pieces, with a 2-1-1-2 layout. The manufacturer claims that there are 3 ED lenses in the lens barrel, so in addition to the objective lens, the eyepiece group and the flat field lens may also have ED lens .

Abbe prism

However, what I said is only a personal guess, because from the cross-sectional view, Nikon did not say whether it is 7x50 or 10x50. Can you think that the two telescopes use the same objective lens and prism, followed by a flat field lens and a more complex eyepiece?

Abbe prism and primary mirror comparison

Since it is born for performance,Without compromise, the objective lens coating is also the best. Nikon claims that all air surfaces use the best multilayer coating, and the prisms also have phase coatings.

If it is used for stargazing, can such a complicated optical structure guarantee the light transmittance of ? Obviously this mirror has so many air surfaces, roughly 20? Even with the best coating, each film will lose 0.2%-0.3% (visible light) when direct light comes in. Let us assume that a loss of 0.25%, then 20 is 5%. However, it is also necessary to consider the decrease in coating efficiency, especially far away from the visible spectrum region, because mirrors are optimized for visible light bands, and there are some large angles of incident light. Ultra-wide-angle eyepieces have some extremely large angles. Take these into account. Going in, it's not surprising that you lose 10%.

Nikon WX Centennial Edition

This is not over yet, if it is a simple mirror, we just say that the coating is OK, and the light absorption problem can be ignored. It is reasonable to say that, because modern mirrors are optically clean, and the light path is very short as a small mirror, so the problem of light absorption is secondary compared to coating. But as Nikon WX has such a long light path and so much glass, this aspect still needs to be considered.

Nikon WX regular version

We don’t know what glass Nikon uses, but we can imagine that Nikon must use the best glass, just like some top mirrors use Schott HT glass. . SCHOTT’s top glass 400 nm absorbs 0.2% in one centimeter of optical path. The bigger problem is the prism, because you have to use Bak4, even if you use SCHOTT HT, it will lose 0.7%. Of course, you can also use SK glass, the absorption rate is reduced to 0.4%.

We can guess the light path of WX through the cross-sectional view. Using the pixel marking method, we can probably get that the light path of WX is 13 cm long.Half of them are in the prism. In general, you have to add 6-7% blue light loss. The light loss in the middle and red parts of the visible spectrum is much smaller.

Nikon WX eyepiece close-up

The lens body is made of magnesium alloy, and the part that is held by hand is covered with a layer of leather. The eyepiece has 6 positions, and the end of eyepiece is rubber. Material. In addition to these, nitrogen is flushed in the mirror body, which is waterproof up to 5 meters (10 minutes).

Buyers can get a good aluminum alloy case, leather objective/eyepiece cover, a tripod adapter and two straps (one for the mirror and the other for the case). The mirror itself comes with a 10-year warranty.

WX Nikon accessories

measured

objective lens diameter measured: -50 mm left and right -50 mm actual multiples

: 9.97 times

transmittance: 85%

color: The center is excellent,The edge of the middle level

divergence: negligible tip star point

distortion : from the field of view radius