（翻译）评测：Nobilem 8x50 B/GA vs. Jenoptem 7x50W vs. DF 7x40

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原文来自http://www.holgermerlitz.de/nobilem8x50.html
Review: Nobilem 8x50 B/GA vs. Jenoptem 7x50W vs. NVA DF 7x40
by Holger Merlitz   翻译 北旅论坛footway
In this review I want to compare three interesting binoculars suitable for use under low light conditions. Such instruments have to be equipped with a large exit pupil diameter, i.e. large objectives at comparably small magnifications. This is an in-house competition between three Zeiss Jena binoculars, produced in three different decades and nowadays available on the second-hand market.
本评测中我想比较三款适合低照明使用的令人感兴趣的镜子。这样的镜子必须有大出瞳直径，也就是大物镜直径和相比之下的小放大倍率。这里是三款Zeiss Jena镜子的兄弟间比较，生产于三个不同时代，如今能在二手市场买到。

Fig.1: The NVA DF 7x40.
The DF 7x40 was produced during the 60s and 70s for the East German Army NVA (Nationale Volksarmee). It can be regarded as an all-round glass with some low-light capabilities, as to be expected for a border control ('Checkpoint Charlie') binocular. A description of this device was given in another review. The DF can be found in large quantities at e-bay for 200 Euro in good condition.
DF7x40是1960和1970年代为东德军队(Nationale Volksarmee)生产的。它可看作是兼有低照明能力的多功能镜子，是用来进行边境控制（检查站人）的镜子。在另外评测中有描述。在e-bay上有大量DF，好品相的能卖200欧元。

Fig. 2: The Zeiss Jena Jenoptem 7x50W.
The Jenoptem 7x50W, with more than 7mm exit pupil, is a real night glass. It was probably produced during the 80s. Things are a little confusing because sometimes one can read that the Jenoptem was the successor of the Binoctem, now with multi-coated optics, but there seem to exist Binoctems with multi-coating as well. The smaller 8x30W version was tested here, and the third of the line, the 10x50W, was tested here. The Jenoptem 7x50W appears frequently on e-bay for about 150 Euro in good condition.
拥有超过7mm出瞳直径的Jenoptem 7x50W是真正的夜用镜，可能生产于1980年代。有时会有小误会，认为认为Jenoptem是Binoctem的有多层镀膜的继承者，但Binoctem也有多层镀膜版本。更小的8x30W版本在here被测试，另一款10x50W在here被测试。E-bay上经常出现Jenoptem 7x50W，好品相的卖150欧元。

Fig. 3: The Nobilem 8x50 B/GA
The Nobilem was the high end line of East German Zeiss binoculars for the civilian market. I am citing the history section of the Docter home-page:
"From the middle of the 70s onwards new developments again became a focus. The binoculars models 8x32 and 10x40 with in-line optics also originated at this time. However, the excellent telescopes NOBILEM 8x50 and 12x50 with first-class performance were only produced for a short time due to the huge efforts needed and the technical demands involved. In the middle of the 80s they were replaced by models of the same name, which were the results of extensive concept studies. This model series has step by step been complemented by further models and variants and has been redesigned over the recent years."
Nobilem是东德Zeiss为民用市场生产的高端镜子，我引用了在Docter主页的关于它的历史部分：
“1970年代中期前，新产品再次被关注。此时创造出8x32 和 10x40直筒（in-line）镜。但，优秀的拥有最高水平的NOBILEM 8x50 和 12x50只生产了很短时间，原因是高昂的成本和复杂工艺的需要。在1980年代中期它们被同名产品替代，该同名产品是经过广泛调查研究的成果。通过逐步增添新型号、新变种而逐步扩充系列，到最近已全被重新设计过了。
In 1991, after collapse of the GDR, Docter Optic took over the Zeiss binocular production plant in Eisfeld and is since then continuing the Nobilem line. Also, the EDF 7x40, the successor of the DF 7x40, is still in production as a modified civilian version (without IR detector). In the current brochure, however, I can't find the Nobilem 8x50 any more, only a 8x56, 10x50, 15x60 and various 7x50 devices. I still found one 8x50 B/GA in new condition for 360 Euro, including 30 years of warranty. The price tag already indicates that these units are aiming toward the upper class section of the market, although there is still a gap left to the other noble brands. The "B" refers to "Brillentraeger", i.e. with long eye relief and therefore suitable for spectacle wearer, the "GA" means "Gummi Armierung", i.e. rubber armoring.
1991年，东德的解体后，Docter Optic在Eisfeld接管了Zeiss的望远镜生产，自此继续生产Nobilem系列。作为DF7x40后继者的EDF7x40的修改过的民用版本（取消了红外探测）也继续生产。不过在最近的名单上，我再也没找到Nobilem 8x50，只有8x56，10x50，15x60和各种7x50产品。我还发现全新的有30年保修的8x50 B/GA是360欧元。这价格标签已经指明这镜子瞄准的是高端市场，虽然已经给别的名牌留下了缝隙。‘B’表示Brillentraeger，也就是长出瞳距离适合戴眼镜使用，‘GA’表示Gummi Armierung，表示包胶。

Fig. 4: The DF 7x40, Nobilem 8x50 B/GA and Jenoptem 7x50W

The following table summarizes some of the specifications of the contenders.
下表中是被评测对象的各项指标

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Optical performance 光学性能
Angle of view: Night glasses usually have got a fairly narrow apparent angle of view. In short, the reason for that is this (thanks to Fan Tao for the clarification): If we have the objective diameter D and the focal length F of the objective, then the F-ratio is defined as Fr = F/D. The magnification of the instrument is obtained with m = F/f, where f = focal length of the ocular, hence we have f = F/m = Fr*D/m. But D/m = d is the exit pupil diameter, so we have f = Fr*d. Unfortunately, the F-ratio Fr cannot easily be pushed below a critical value (perhaps around Fr = 4) in order to keep the aberrations under control. In a night glass, the exit pupil diameter d has to be large, which then implies that the focal length f of the ocular has to be long. But wide angle oculars with long focal lengths have large field lenses, which require large prisms to be illuminated to the edges of the field, and this leads to an expensive and bulky instrument. Alternatively, one could reduce the F-ratio and employ highly corrected apochromatic objective lenses, which again were expensive. It is therefore not surprising to find the Jenoptem 7x50 with a rather narrow apparent field of view. 51 degrees is slightly beyond the standard for 7x50 glasses, but it has certainly not deserved the "W" for wide angle. In my opinion, a field of 51 degrees is too less to create fun. The Nobilem 8x50 and the DF 7x40 have got around 60 degrees (which is the lower limit for wide angle glasses) and this is acceptable for this type of binoculars. Wide angle 7x50 binoculars are discussed in another review
视角：夜用望远镜通常只有相当狭窄的视场。简而言之，原因是（感谢Fan Tao的解释）：物镜直径为D，物镜焦距为F，F-ratio可以定义为Fr=F/D。镜子的放大倍率来自m=F/f，这里f是目镜焦距，因此我们得到f=F/m=Fr*D/m，但D/m=d是出瞳直径，所以f=Fr*d。不幸的是，Fr不能那么轻易的低过一个临界值（大约是Fr=4），为的是保持像差（也可能是色差,译者）可控。在夜用镜子中，出瞳直径也必须很大，意味着目镜焦距也必须很大。但宽视野又长焦距的目镜含有广角镜片，这需要大棱镜照亮视场边缘，导致价格昂贵和体积巨大。另一选择是，可减少F-ratio并使用高消色差物镜，又使得价格升高。所以不要惊讶于发现Jenoptem 7x50有那么小的51度视野，仅仅超过了7x50镜子的一般标准，它的确没有广角标志“W”。我的观点是，51度视野远不够创造乐趣。Nobilem 8x50 和 DF 7x40有60度视野（是广角镜子的最低界限）是这镜子的可接受之处。广角7x50镜子在另外评测中讨论。

Image sharpness: The DF and the Jenoptem display a similar pattern: Very sharp in the center and an increasing softening toward the outer 75-100% of the radius. Star observations are even more selective: The star images remain point-like within the innermost 60% of the radius and almost disappear at the outer edge of the field. It sometimes seems that the Jenoptem is a little sharper in the center, but the DF is keeping a high level of accuracy over a wider field. Very obvious, however, is the fact that the Nobilem performs best here. Stars remain point-like up to 80% of the field and the aberration remains moderate even at the edge. The aberration control of the Nobilem thus shows a visible improvement over the elder generation Zeiss glasses.
图像清晰度：DF和Jenoptem有相似的格调：中间非常清晰，从半径75%开始逐渐变软。观星测试更具有淘汰性：星像在60%内保持点装，但到边缘几乎消失了。有时感觉Jenoptem在中心比DF更清晰，但DF在全部视场都保持高度精确性。然而，显然的事实是Nobilem表现最好，星像能保持到80%，即使在边缘，变形程度也在中等。Nobilem对像差色差的控制显示了相比老一代的Zeiss镜的明显的进步。

Image color: The image of the DF has got a slight yellowish tint. Not on a disturbing level, but noticeable when compared to the other two contenders. The Nobilem appears to be a little yellowish, too, less than the DF but also not completely neutral. In my opinion, the Jenoptem conserves the colors best, but the differences to the Nobilem are subtle.
图像颜色：DF有轻微的偏黄，没到令人烦恼的水平，但与其它两款比较是显而易见的。Nobilem显示了少许偏黄，比DF轻，但也不是完全无色。在我看来Jenoptem是最不偏色的，但和Nobilem的区别是细微的。

Rectilinear distortion: All three glasses show a slight pincushion distortion to eliminate the globe effect of the panning binocular.
直线畸变：三款镜子都有轻微的枕形畸变为的是消除移动观测的滚球效应。

Stray light: The following situation is a selective test for stray light: You are looking over a clearing to observe the edge of the woods. It is one hour after sunset, the forest is already gloomy but the sky is still quite bright. Its light is entering the objectives and illuminates the inner objective tube walls. A part of this illumination is scattered into the optical path and entering the eyes as a diffuse stray light, reducing the contrast of the image. A glossy finish of the inner tube walls can contribute a lot to enhance this effect, baffling and a well dimensioned prism housing help to suppress the same. Stray light can become an issue under twilight conditions, and that's where night glasses are frequently used, and corresponding care has been taken in the construction of the three contenders. The DF essentially shows no stray light at all. A look at Fig. 4 reveals the obvious explanation for that: The DF practically has no objective tubes; the prism housings begin just behind the objectives and are wide enough to prevent scattered light invading the optical paths. The objective tubes of the Jenoptem and Nobilem are well baffled and stray light, although visible, remains on a moderate level. It is a bit surprising to find that the Jenoptem actually performs better than the Nobilem. In fact, Fig. 4 also shows that the Nobilem has long tubes and short prisms, whereas the Jenoptem has shorter tubes and longer prisms. One may speculate whether this makes the Jenoptem less prone to stray light.
漫射光：下面部分是针对漫射光的选择性实验：寻找森林边缘的小块空地。当太阳落山后1小时，森林是黑暗的但天空依然完全明亮，天空光线穿过物镜照亮镜筒内壁，部分光线散进主光路，最后作为没用的漫射光进入眼睛，减少了画面的对比度。一个光滑的内壁表面能显著的增强这个效果，带有阻碍的有充足体积的棱镜室能抑制漫射光。漫射光在黄昏时经常出现，这也是夜用镜经常使用的时间，这三款镜子结构上都有相应的措施抑制漫射光。DF根本就没有漫射光，看看图4就能找到显而易见的理由：DF事实上就没有物镜筒；棱镜室的就在物镜后，并且足够大以阻止漫射光线进入主光路。Jenoptem 和 Nobilem 的物镜筒带有阻碍，所以即使能看见漫射光，也保持在中等水平。有一点让人惊讶的是Jenoptem比Nobilem表现的要好。事实上，图4也显示了Nobilem有长长的物镜筒和更短的棱镜室，而Nobilem有更短的物镜筒和更长的棱镜室，有人推测或许这些导致了Jenoptem的漫射光更轻微。

Ghost images: If, at night, a bright object (street lantern, moon) is positioned into the field, reflections on the air-to-glass surfaces take place, which can lead to multiple 'ghost' images of the light source. The Jenoptem is clearly displaying a line of multiple, well localized and fairly bright reflections if a bright light source is positioned close to the center of the field. When shifting the light toward the edge, the reflections disappear. In the Nobilem, only a single diffuse spot appears, but another, diffuse and dim glare appears when the light is shifted outside the field - perhaps the effect of stray light (see above). The DF shows no ghost images in the left tube, but in the right eye, a fairly bright reflection takes place at the reticle, and this one has more intensity than the Nobilem's. However, the effect disappears soon when the object is shifted toward the edge of field. To judge which one of the glasses shows a more disturbing ghosting is not easy. I would give it an even match between the Nobilem and the DF, and a lower performance of the Jenoptem. But one should note that the DF, with reticle removed, would definitely beat the Nobilem.
鬼影：如果在夜晚，一个明亮物体（路灯，月亮）进入了视野，镜片表面发生反射，能产生明亮物体的多个“鬼魂”般图像。如果一个明亮的光源移到视场中央，Jenoptem显现出排成一行的多个，特定位置的，适当亮度的反光。当光源移向边缘，反光消失。对于Nobilem，只显示了一个光斑，但另一镜筒，当光源移出视场，显示了散开的昏暗光线，似乎是漫射光的表现。DF左镜筒没有鬼影，但在右镜筒，刻度板上有一个相当亮度的鬼影，比Nobilem的鬼影强烈些。不过，当移向边缘鬼影就消失了。判断哪个镜子的鬼影更强并不容易。我认为Nobilem 和DF 水平相当，Jenoptem表现差些。但注意的是如果DF的刻度板去除掉，将能干净利落的比过Nobilem。

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Low light performance: It has to be quite dark before differences become obvious. Then, however, it is all the more impressive how the Jenoptem and Nobilem outperform the DF. Their images just remain brighter and show a lot of more details than the NVA glass. Perhaps this is just in parts a consequence of their larger exit pupils: According to the DF's manual, its transmission is 75% through the left tube and 68% through the right tube, and this is not much for today's standards, where transmission rates close to 90% are reached with the help of optimized surface coatings. The DF is still singly coated, the Jenoptem has got a multi-layer coating as well as the Nobilem. After lengthy hours of observation, I was unable to find any difference in the low light performance between the Jenoptem and the Nobilem. This could be related to the fact that at my age (around 35), my eye's pupils won't open up to 7mm any more, so I can't make full use of the light offered by the Jenoptem. If the observer's pupils have 6mm, then the 7x50 Jenoptem is stopped down to 7x42 only. Also, the Docter's brochure explains that the individual prisms of the Nobilem are cemented to reduce the air-to-glass transitions, and this should also contribute to a higher transmission rate and to the good night performance of this binocular.
低照明表现：若要有明显区别必须在相当黑的情况下。这里，虽然，Jenoptem 和 Nobilem超过DF的程度令人印象深刻，它们的图像比NVA镜子的图像更加明亮并能显示更多细节。或许这只是因为是它们更大的出瞳直径，根据DF的手册，DF的左筒透光率是75%，右筒透光率是68%，按照现在的标准并不高，现在的最好的镀膜能让透光率达到90%。DF只是单层镀膜，Jenoptem有和Nobilem一样的多层镀膜。经过很长时间的观测，我依然无法找出Jenoptem和Nobilem在低照明下的区别。这该考虑到我的年龄（35岁），我的瞳孔直径不能再张开到7mm，所以我不能完全接受Jenoptem传来的光束。如果观察者的瞳孔直径是6mm，那么7x50 Jenoptem会被降级成为7x42规格。同样，Docter的手册也解释说Nobilem的棱镜被胶合了以减少界面，这也能提高透光率以成为好的夜用望远镜。

Mechanical construction机械结构
Both, the DF and the Nobilem, are very rugged with a heavy body construction and a thick rubber armoring. The Nobilem brochure touts that a new patented prism holder is employed to improve the sturdiness of the unit. The fact that they mention it so explicitly may have a historical reason: The Jenoptems (actually the heavy ones, the 7x50 and 10x50) had once upon a time got the reputation to get rather easily knocked out of alignment. Obviously Zeiss Jena had drawn the consequence and improved the prism holder in the Nobilem line. Still, the DF, which had to adhere to military standards in terms of mechanical stability and water resistance, feels somewhat more bomb-proof than the Nobilem. It is interesting to note that Docter offers a 7x50 ('Navidoc B/GA') device with individual focus which is fully water-proof. Incidentally, it can also be delivered with a reticle. This one would likely be on the same constructional level as the NVA DF. The Jenoptem with its aluminum body and precisely machined movements offers a flawless construction for those users who are not planning to join a rain forest expedition. Only the eye-relief of this glass is too short to be used with spectacles on, whereas the DF and Nobilem have got fold-in eye-cups with generous eye-relief.
DF和Nobilem都有沉重的躯体结构和厚厚的包胶，表面粗糙。Nobilem手册吹嘘说他们新的有专利的棱镜固定物能提高单元坚固性。事实上他们如此明确的提及这事是有历史原因的：从前Jenoptems (实际上就是更重的 7x50 和 10x50)有这容易震偏光轴的恶名。明显Zeiss Jena已经推翻这情况，在Nobilem系列上改进了棱镜固定。 DF是参照军用镜的标准，如机械性能稳定，防水，感觉比Nobilem更防弹。令人感兴趣的注意是Docter提供双目调焦完全防水的7x50 ('Navidoc B/GA')，也包括分化板，就和NVA DF的结构一般水平。Jenoptem的铝制镜体，流畅的机械运转为那些不去热带雨林探险的人提供了完美无瑕的工具，只是它的出瞳距离太短了点，戴眼镜无法使用，DF和Nobilem能翻折眼罩而提供足够的出瞳距离。

Summary 总结
The following table is supposed to summarize the above observations. The best performing binocular gets three points, the following contenders two and one, respectively. In case several binoculars are ranking equally, their scores are averaged.
下表是上述各性能的总结。表现最好的镜子得3分，后面的分别得2和1。如果几个镜子的排名同样，它们的分数取平均。

Again, a warning regarding the 'final score' is adequate here: The higher number in the final score does not necessarily mean that a binocular is better, because this is just the numerical sum of scores it received for the various features. It is always required to figure out which of the features are of high relevance for the user and which are not, and this depends on the intended spectrum of application.
再次警告，上面的最终分对下面合适：最终分更高的并不意味着这镜子更好，因为这只是各个不同方面的分数的和。经常被要求指出哪个方面的品质更适合用户哪方面不是，这些需要考虑到应用的各个需要。

The Jenoptem cannot quite match up with the other two contenders. But a closer look reveals that its deficiencies are essentially rooted in constructional aspects like mechanical ruggedness and angle of view. If these are of little relevance, the first and the last column of the table may be skipped and suddenly the Jenoptem is as good as the DF or Nobilem. When it comes to image quality, the Jenoptem is competitive with the more costly devices, but at a reduced field of view.
Jenoptem完全无法与其它两个竞争者比赛，但靠近观察揭示了它的不足，本质根源在结构方面，比如机械坚固性和视野，如果这方面稍微合适点，这表的第一和第三会改变，Jenoptem和DF和Nobilem一样好。谈到像质方面，Jenoptem比更贵的镜子更有竞争力，但视野减小了。

As it was to be expected, the DF and the Nobilem had a tough competition. With the reticle removed, the DF would take away another point from the Nobilem because then the ghosting in the right eyepiece were diminished. The question then arises whether the Nobilem is actually worth the extra money. The answer is: Yes, if low light performance has got a high priority. Here the DF definitely cannot match. The specification of the Nobilem, 8x50, also suggests it to be used as a general all-round glass. As such, however, the DF is also competitive, costs half the price and has got a margin in terms of water-resistance and ruggedness. One may speculate whether this could be the reason why Docter has discontinued the 8x50 model. With more and more DFs showing up on the surplus market in recent years, the 8x50 had got too much of competition - ironically from devices of the same factory! The construction of the DF, with a short and stubby body, seems to have one advantage when it comes to stray light suppression. It is interesting to note that the early Nobilem-S models of 1980 were built with a similarly shaped body. The later reconstruction of the Nobilem series then led to the present appearance with smaller prism housings and longer objective tubes. I can only speculate whether the short form employed objectives with shorter focal length which caused a nightmare to keep them free of chromatic aberration. At least in the DF, or its civilian version, the Septarem 7x40, this construction principle was realized, and successfully so.
和预期的一样，DF和Nobilem最具有竞争力。如果分化板被拆除，DF能从Nobilem里再得到一分，因为这样右镜筒的鬼影就减轻了。有个问题就是难道Nobilem真值得付出额外的钱吗？答案是：如果低照明表现有高优先级的话，值得。DF明显不能攀比。Nobilem 8x50的规格也暗示这也能作为通用镜子，同样的，DF具有竞争力，花一半的价格就得到一个防水的可粗用的好镜子。有人会推测这也是Docter停产8x50规格的原因。随着越来越多的DF出现在剩余物资市场，8x50有了太多的竞争者——竟然是同厂产品。DF的结构，短小粗壮的身材，看起来对抑制漫射光相当有利。令人感兴趣的是更早1980年的Nobilem-S也有类似的身材，后来的Nobilem系列的身材展现了较小的棱镜和长长的物镜筒。我只能推测是否物镜焦距的的缩小对于控制色差像差是个噩梦，最后在DF，或者它的民用版本Septarem 7x40，这个结构实现并成功了。

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Disclaimer 声明
The information given in this report reflects the personal impression and opinion of the author only. I cannot guarantee for the accuracy of any given specification. I have neither been payed nor have I been supported in any other way to write this review.
在本报告中的资料反映了个人的印象和作者的见解而已。我不能保证任何特定规格的准确性。写这个报告我没有得到任何付费和任何支持。

Links
Docter Optics
Fan's Binocular Collection
An interesting article (in German language) about the construction of the Octarem 8x50 (which is almost identical to the Nobilem), published in 1985 in the Jenaer Rundschau. Thanks to Sebastian Rabus for scanning this document!
一个有趣的关于Octarem 8x50（和Nobilem几乎相同）的文章（德语），1985年Jenaer Rundschau出版，感谢Sebastian Rabus扫描了该文件。
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Last updated: 2003

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现在用小猫上网，一个网页就能占满带宽，15年前的上网速度，高级享受。
祝大家春节快乐。

footway

自己顶一下，真不该年前发贴，没人看。年后又沉下去了。

歪歪

这帖子应该似乎放入收藏类望远镜区去合适一些