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发表于 2007-9-4 13:57
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望远镜的购买——选择的的智慧[欢迎斧正]
Binocular purchase: Collected wisdoms
望远镜的购买：选择的的智慧
by Holger Merlitz
Over a period of 2 years I was scanning the binoculars markets. During that time, I had purchased close to 50 instruments, the majority of them as second hand items, many of them sold again. The more interesting items had to undergo a careful test procedure, leading to those 14 comparative test reports found somewhere else on my web-site. Also, a few binoculars were provided exclusively for testing by vendors who were keen on seeing their products being compared in my reviews. With their support I was able to extend the performance spectrum of my test-candidates towards the high-end region.
我对望远镜市场的关注已经超过两年了。在这段时间里，我买了接近50个镜子，大部分都是二手的，有些还被转卖过多次。想比较于一手交钱一手交货的最后交易，更有意思的是买镜前必须经历的仔细检查。因此也就有了我网页上的14篇的比较测试报告。当然，有一些送检的镜子是由卖家提供的，他们非常想知道这些镜子在我这儿得到的评价。托他们的福，我也就因此通过送来参检的高端镜子拓宽了我的用镜体验。
／*The more interesting items had to undergo a careful test procedure*／
The selection procedure for my survey was naturally biased to rather easily available items on the European and especially on the German market. If one compares the offerings on Ebay Germany with Ebay US, it immediately becomes clear that the subset of binoculars frequently found on both of them makes less than 50% of the total. It doesn't need much of investigation to realize that my selection contains an un-proportional high number of Porro type binoculars, many of them being military instruments and quite a few of them being of East European origin. This reflects my personal focus of interest, of course, however - just in parts. Actually, this is also a natural result of a selection procedure, driven by the desire to optimize the price-to-performance ratio. In the following remarks I shall frequently come back to the most essential question of every binoculars user: How could I find the maximum performance for my needs and for the money I am willing to spend?
我挑镜的选择过程是基本上基于欧洲市场上那些容易找到的镜子的，尤其是在德国市场上的。如果有人比较一下Ebay德国和美国，它就会发现在两个市场上同时都能找到的镜子不超过总数的50%。很明显在我收集的镜子中保罗镜占了很大的比例，其中很多都是军镜并且有几个还是东欧血统的军镜。这表明了我的个人嗜好，当然只是一部分的嗜好。实际上这也是选择的自然结果，是由性价比决定的。在下面的评论中，我将经常提到对每个镜友在购镜时的最基本问题：是光学至上，还是量力而为？
Wisdom No. 1:
There are no usable binoculars for less than 50 Euro/Dollars
智慧 1
50欧以下的镜子都是烂镜子！（可用镜子的价格是不会低于50欧元／美元的）
Optical instruments do not only require a high precision optics but also a mechanical framework which keeps the construction in proper collimation. A handheld binocular is not a stationary device, but carried around and thereby taking mechanical and thermal stress and still having to keep its internals fixed on a scale of a few hundreds of mm. This can't work out for a few bucks, neither in China nor anywhere else around the world ("you cannot make a Rolls-Royce out of steel wool by just adding water", Bill Cook on Cloudy Nights). The huge amount of 'night-active', 'ruby-coated', camouflage painted plastic binoculars offered on Ebay for 20 Euro or less are complete rubbish and not even worth to be considered as a toy for the kids. The cheapest binoculars which satisfy the minimum requirements of delivering a sharp image within 50% of the field and which come with a body where at least the prism housings are made of metal are found in the 50 Euro region. Ok - a few Russian binoculars are there for somewhat less. But although these are usually made of metal and sometimes even come with a reasonable coating, their state of collimation seems to be a random variable and it sometimes needs to order a couple of them before finally having one of proper performance. While the low-end Chinese binoculars are useless, their middle range, as sold for 50 Euro and above, comes with a mechanical construction which is often superior to the Russian glasses of same price. However, they are often lacking in their quality of coating and tend to produce excessive ghost images of bright objects.
光学器件并不只要求在光学上的精密，还需要可以保持光学结构稳定的机械架构。手持望远镜并不是一个静止的摆设，而是要经常带出去的。因此，在机械操作和热压变化时都要保持内部光学器件的配合精度在百分之一毫米的范围内。要做到这一点不是十几块钱可以搞定的，不论是在中国还是其它任何国家（“你不可能光对着一堆铁和羊毛浇水就能造出劳斯莱斯！”－－比尔。库克）。在Ebay上，有一堆打着“夜视”、“红膜”还有迷彩包胶的镜子卖大约20欧或者更低。这些都是真正垃圾，连给小孩当玩具都不配！能满足至少50% 视野内清晰成像并且使用金属棱镜室这样最低要求的镜子大约要卖50欧左右。OK，有一些俄国镜子是在这个价位的，而且有个别俄镜的价格更低。虽然它们都是金属的而且有些还有像样的镀膜，但是它们光学上的个体差异较大。有的时候你要从一对镜子中才能跳出一只还凑合的。低端的中国镜子也是垃圾，不过中档的（售价在50欧或更高的），在机械结构上就比同价位的俄镜好太多了。可惜，这些镜子在镀膜上失分较多，而且在观察明亮的物体时容易产生鬼影！
/*and thereby taking mechanical and thermal stress and still having to keep its internals fixed on a scale of a few hundreds of mm*/
Wisdom No. 2:
If a binocular has to be rugged and cheap, look around for (second hand) military devices
智慧 2
想要既便宜又粗壮的镜子，你还是去找二手军镜吧！
In most cases, such a military binocular is of Porro type with individually focusing oculars. This type of construction is comparably simple and therefore cheap, and the individual focuser allows for a much easier sealing against environmental hazards (dust, humidity) than any standard central focuser. In recent years some cheap "water proof" Porro binoculars with sealed central focuser have shown up, but, as a side-effect of the sealing, they focus inaccurately and do not deliver sharp images. Roof prism binoculars usually come with internal focuser and are easier to seal up, but are generally of higher price for a given optical performance. A military binocular provides a fairly decent optical performance and has been tested to survive a considerable amount of mechanical abuse. The smaller versions of them, typically of 8x30, are found on Ebay from 80 Euro onwards, depending on condition. It is also possible to purchase new military binoculars for little money: The Russian BPO are available for about 120 Euro (BPO 7x30) or 140 Euro (BPO 10x42). Of course, these are not without shortcomings, having a strong yellow tint and being somewhat prone to ghost images.
大部分情况下，军镜都是双调保罗的。这种结构相对简单，因此成本低。而且双调结构比任何中调镜子更容易密封，防止环境危害（灰尘、湿气）。近几年有些中调防水的保罗镜面市了，不过最重要的光学性能却不怎么的：成像很软。中调屋脊镜比较容易密封，但是就它的成像效果而言普遍价格较高。军镜的光学表现还是很不错的，而且通过耐用性检测经得起粗用。较小的军镜一般都是8x30的，在Ebay上按照品像不同，大约80欧左右。当然你也是有可能花很少钱买到新军镜的：军版全7大约120欧，全10大约140欧。当然，它们也不是没有缺点的，大黄筒而且有鬼影。
Wisdom No. 3:
Over the decades, the quality of coating was the most influential factor for optical performance
智慧 3
镀膜的质量是影响镜子长时间表现的最主要因素
Already during the 1930s, top performance binoculars were engineered for military use. During WWII, some of them were already equipped with a single layer anti-reflection coating, which was since then continually improved, leading to better contrast, brightness and color rendition. The introduction of multi-layer coating in the late 1970s has caused another performance boost. Since that time, the color saturation of the image reached that high level we are used to find with modern optics. Binoculars of roof-prism type experienced a final performance jump in the late 1980s when the phase-shift coating was introduced. Since that time (but not before), the best roof prism binoculars approached the contrast offered by high-end Porro prism glasses. This historical development had its implications on the performance of ancient binoculars, regardless of their quality. For example, the Porro binoculars made by Zeiss (Oberkochen) in the 1950s were excellent enough to be even competitive with today's high end binoculars - if they just had a modern coating. With the technology available at that time, however, their colors appeared rather pale when compared to a modern binocular. This is the rule of thumb for anybody who is looking for a second hand binocular with maximum performance: If it is a Porro, it should have been made after 1980 (availability of multi layer coating), if it is a roof prism, then not earlier than 1990 (phase-shift coating).
早在二十世纪三十年代，顶级的镜子都是为军用目的而设计的。在二战时，已经有一些军镜开始使用单层增透膜了。从那时起镀膜技术不断向更高对比度、亮度、色彩还原的方向发展。随着二十世纪七十年代多层镀膜的发明，镜子的表现力有了一个极大的提高。从那时起成像的色彩饱和度达到了一个很高的水准，正如我们现在镜子所表现的那样。当二十世纪八十年代时相位膜发明后屋脊镜的成像有了极大的提高。从那以后顶级屋脊镜的对比度接近了顶级的保罗镜，而此前是不可想象的。这种历史性的突破在成像表现方面对早期镜子有很大冲击，而镜子本身的质量则不受影响。比如：上世纪五十年代蔡斯(Oberkochen)生产的保罗镜和现在的顶级保罗镜都有一比，如果它们也使用现代镀膜的话。由于受当时技术条件的限制，它们的色彩饱和度都比不上现代的镜子。所以对二手镜子光学表现有要求的买家而言，这里有一条基本原则：要是买保罗镜，最好是1980年以后的（使用了多层镀膜），如果买屋脊镜，就别买1990年以前的（相位膜没有使用）。
Wisdom No. 4:
Optical top performance is already available for 700 Euro - beyond that, binoculars become more compact and versatile.
智慧 4
有顶级光学表现的镜子700欧就够了，价格更高的话，镜子只是在体积和重量上更小。
The top line Porros of Fujinon (e.g. 10x50 FMT-SX) and Nikon (e.g. 10x42 SE) are good enough to match the optical performance of any other high-end binocular and cost around 700 Euro. But, being of Porro type, they are somewhat heavy and bulky. Additionally, the Nikon SE is not waterproof, and the Fujinon has got uncomfortable, individually focusing oculars. None of them comes with features like twist-up eye-cups or a close focus distance of 2m. In contrast, the high-end roof prism binoculars of Zeiss, Leica and Swarovski are offering almost everything at once: Compact and lightweight body, central focuser and water resistance, but they cost significantly more without being superior (for any practical purpose) in their optical performance.
在700欧左右的富士(比如10x50 FMT-SX)和尼康(10x42 SE)顶级的保罗镜在光学表现上已经是顶级的了。不过由于是保罗结构它们体积稍大、重量稍重。除此之外SE是不放水的，而FMT的双调目镜很难用。它们也没有什么旋升眼罩或者最近对焦距离2米这样的特色。相比较而言，蔡斯、莱卡和施华的顶级屋脊镜几乎配置了所有的东西：紧凑而轻量的镜体、中调防水等。不过它们的光学表现并没有比顶级保罗有更大提高（在任何实际的层面上），可它们的价格却大大提高了。
Wisdom No. 5:
The most versatile binocular is the 8x40
智慧 5
最有用的规格是8x40
The wide range of specifications found in binoculars is confusing to the unexperienced. Most people tend to select a glass with unnecessary high magnification, e.g. 10x, thereby sacrificing angle of view and stability of image. Others believe a binocular has to provide an exit pupil as wide as possible to be usable under twilight conditions. But those glasses with 7mm exit pupil (7x50, 8x56, 9x63) usually come with an annoyingly small apparent angel of field ('tunnel view') and are, due to large objective diameters, heavy pieces of glass. When used in real life, the eye-pupils then hardly reach those 7mm, and this only for observers in their young ages, so that parts of the collected light are almost always wasted. Finally, there are ultra-light compact glasses, designed for the mobile user. But these come with small prisms and a corresponding small field of view, and their exit pupils (typically 3mm) are narrow so that these binoculars quickly become useless under dim light conditions. The best compromise is a device with around 5mm exit pupil and a magnification which allows to produce a firm and stable image under less than ideal conditions, i.e. not beyond 8x. Therefore, the 8x40 binocular appears to be the best all-around glass. Even as a wide-angle (beyond 60 degs. apparent field of view) and equipped with a proper mechanical ruggedness, these glasses weight no more than 800g, can be taken out on every trip and are reasonably suited for low light applications, too.
对于初哥而言各种规格的镜子是很让人困惑的。大部分人倾向于选择并不实用的高倍，比如10倍的镜子就牺牲的视角而且轻微的抖动都会使成像不稳定。另一些人认为镜子的出瞳直径越大越好，以便在黄昏和黎明时也能使用。但是那些有7mm出瞳直径(比如7x50, 8x56, 9x63这些规格)的镜子表观视场几乎都很小('隧道视场')，这很让人烦。而且这些大物镜的镜子，分量都是很沉。当实际使用时，瞳孔是很难有扩到7mm的机会的，这只在镜友在年轻时才会有。所以物镜所收集的光线几乎总是被浪费的。最后我要提到的是那些为外出使用而设计的超轻量级镜子。这些镜子由于使用了小的棱镜所以视场也相应的小，而且由于出瞳直径小（一般不超过3mm）所以一旦光照条件降低这些镜子很快就力不从心了。最好的折衷产品是有5mm出瞳直径并且放大倍数（比如8倍）能够能使非理想条件下的成像结实、手持稳定。因此，8x40 是可能最有用的规格。尽管视场很大（表观视场在60度以上），机械强度也合适，这类镜子的重量也不会超过800克。所以你可每次出游都带着它，而且低光照条件下也能用。
/*tunnel view*/
Wisdom No. 6:
Tests are helpful to evaluate middle class binoculars - and losing significance toward the low- and the high-end
智慧 6
测评有助于评价中档镜子，但是对于高端和低端的镜子就没那么有效了
The idea behind a test report is simple: To pre-inform somebody about strong and weak sides of a binocular he possibly never had been able to hold in his own hands. Instead, such a review was created by somebody else, including all those potential obstacles like individual experience and personal preferences. This limitation remains of little relevance as long as the binocular is imperfect enough to exhibit a sufficient number of technical faults the reviewer is then able to point on. In this case, each half-way experienced tester should come to more or less the same conclusions. Things become different once a binocular approaches a state close to perfection, like these 'beyond 1000 Euro cruisers' of Zeiss, Leica, Swarovski or Nikon's top line. It becomes increasingly difficult to discriminate their performance by technical means alone. At this point, individual preferences of the reviewer tend to become the dominating factor for the outcome of the evaluation. My suggestion is therefore: Don't waste your time reading test reports on high-end binoculars, but make sure to get one sample glass and try them out yourself. Technically, any of them will be good enough. It is left to your own decision which one is going to be your personal favorite. Another, totally different problem shows up when testing the low-end side: These binoculars are often of mediocre mechanical construction and may display a wide range of de-collimation even at the time of purchase. This is frequently the case with cheaper products made in Russia and China. The test instrument may then not represent the performance level of the series, but just a random selection, and the test result is of limited accuracy and validity.
评测的目的其实很简单：就是让那些可能无法亲手试用的镜友提前知道一只镜子的好坏。相应的，这类报告都是由别人写的，而那些潜在的缺点都是由个人经验和个人标准定出的。当某只镜子差到能够显示出足够多技术问题让测评人能指出的时候，这样的局限会使报告毫无参考价值。在这样的情况下，每一个经验不是特别老道的测评人得出的结论大体上都是相同的。但是当一只镜子已经接近完美时，比如达到那些超过1000欧的莱卡、蔡斯、施华还有尼康的顶级镜时，测评就比较困难了。你很难只从技术的角度来区分它们的光学表现。就这一点而言，每个独立的评测人都容易让自己的感受主导整个测评。我的建议是：不用浪费时间去读关于高端镜子的测评，直接去找个样品去亲自试一下。在技术层面上，任何一个镜子都足够的好。所以你只要按自己的喜好去买就行了。另一个完全不同性质问题是关于低端镜子的。这类镜子的机械性能普通而且个体差异很大。通常这些镜子都是俄国和中国生产的。而参检的镜子并不能代表这种镜子的整体水平，而只是一个独立个体的表现。所以频测得结果准确性和有效性很有限。
/*Instead, such a review was created by somebody else, including all those potential obstacles like individual experience and personal preferences.*/
Wisdom No. 7:
Large objectives deliver more light, not resolution
智慧 7
大物镜只是汇聚更多的光，而不是提高分辨率
The power of any hand held binocular is low enough to ensure its theoretical resolution limit being far beyond whatever could be resolved by the human eye. In this regime, resolution solely depends on magnification, not on objective size. A switch from 10x30 to 10x50 has therefore no effect on resolution at all. However, the light input is increased, and this may, depending on viewing conditions, lead to improved contrast and thereby to images with additional fine details. Quite generally, one may claim the performance of hand held binoculars (of a given power) being contrast-limited, not resolution-limited. Many other factors, including stray light protection, suppression of reflexes by optical surface coating, reduction of residual aberrations and even the choice of the image's overall color tone are of crucial influence on the level of contrast. This is one reason why quality binoculars show actually more within a wider range of light situations than cheaper binoculars (another reason is related to their superior mechanics and, along with that, a higher level of collimation). It is not only size that matters.
手持望远镜的实际分辨率远小于它的理论值，而人眼也无法达到那种程度。在这种情况下，分辨率仅取决于放大倍数，而不是物镜的尺寸。所以10x30到10x50的规格变化并不能提高分辨率。但是这样会使光线汇聚更多，在某些场合会提高成像对比度，并且会使成像的细节更多。笼统的讲就是手持望远镜在倍数确定后，只是对比度受限而不是分辨率受限。当然还有其它因素影响，包括消光装置——抑制光学部件表面镀膜的反光，减少剩余色差甚至对镜子整体成像色调的选择都会对于镜子的对比度有重要的影响！这就是好镜子比差镜子在更广光照条件下表现更好的一个原因（另外一个原因是好镜子的机械性能优越，因此调较得更好）。所以成像好坏并不只是物镜尺寸大小那么简单。
Wisdom No. 8:
Medium range binoculars deliver a reasonable performance-to-price ratio
智慧 8
中档镜子有很好的性价比
The graphic displays approximate price and relative performance of several 8x30 (8x32) binoculars. It is not to be taken too serious, since obviously there cannot exist any single variable that stands for 'performance'. Still, it helps to demonstrate one fundamental property of the market: Quite generally, performance increases with price, but the gain is slowing down towards the high end sector. Starting with the 50 $ range (there exist cheaper glasses, but see Wisdom No. 1) we are able to find binoculars of already decent quality. For example, the BPC is a somewhat crude, but successful attempt to copy the CZJ Deltrintem. The original is better, but at least twice as expensive, second hand. The medium range starts at about 200 $, where reasonable optical performance is often paired with water resistance and an improved level of ruggedness. Between 200 $ and 600 $, the performance gain is considerable and cannot be repeated, even after adding additional 800 $ for a Zeiss FL. This is the reason why medium range binoculars play an important role in the market. They are driving performance up to a level where differences to the top class become negligible in the majority of viewing situations, while keeping the price on a moderate level.
这张图大致标出了一些8x30 (8x32)镜子的性价比。It is not to be taken too serious, since obviously there cannot exist any single variable that stands for 'performance'.（这句翻译不好）当然，这张图有助于展示市场的基本属性：大体上性能是随着价格上涨的，但是增长率是在不断减少的。首先从50欧左右的开始（其实还有更便宜的，不过建议您再看一下智慧1），我们还是可以找到一些质量还可以的镜子的。比如全7就是一只做工稍粗糙，但是还是很好的继承了蔡8的镜子/*本人对此深表怀疑，至少那个目镜绝对是原创*/。蔡8当然更好，不过二手的价格就至少超过全7的两倍了。中档镜子从200欧开始，光学性能都不错而且经常是防水的，耐用性也上了一个档次。在200到600欧之间的镜子在光学性能上的提升是很可观的。而且像这样的光学提升程度是无法再现的，即便你再加800欧买下蔡斯FL（/*那也不会比600欧的镜子光学性能翻番*/）。这就是中档镜子在市场中占有重要位置的原因。这些镜子可以达到高端镜子的大部分性能（在一些细小的方还是有差距的），而价格还是可以承受的。 |
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。当然，感光元件也会影响到镜头分辨率，二者必须相互配合。在各方面都较理想的情况下，最好的镜头分辨率可达到150l/mm的惊人水准，而许多狗头则不超过30l/mm，想像一下在1毫米的空间里放300根线是什么概念！ 五.鼠标的分辨率：cpi、fps。cpi指每移动1英寸鼠标产生的脉冲数，通俗的说这个量表示的是为了能被人观察到的屏幕上的变化，鼠标必须移动的最小的距离。这个指可以由鼠标驱动或软件（游戏）的设定来改变，但其中最基本、最细微的变化只能是光标移动1个像素。我们下面就讨论1个像素变化的情况。而鼠标必须移动的最小的距离，是cpi的倒数。假设某鼠标是200cpi，那么这个鼠标A必须移动1/200英寸，屏幕上光标移动1个像素。而另一各800cpi的鼠标B，只须移动1/800英寸，光标就能移动1个像素；fps主要应用于光电鼠标中，指感应元件每秒拍摄的帧数，即光学采样率。目前高端鼠标可达到2100cpi或6500fps的水准，每秒钟刷新6500次，很惊人吧！？ 六.在天文学上，分辨率用几何角度来衡量，它表示天文望远镜所能区分最靠近的两个天体和人眼之间的视角，即最小分辨角。天文观测者对分辨率的渴求大概是最高的，因为对他们而言分辨率和亮度意味着一切。 从物理角度出发，望远镜分辨率通过夫琅禾费圆孔衍射实验测定（如图）
