|
|
本帖最后由 footway 于 2010-1-12 20:19 编辑
The following table summarizes some of the specifications of the contenders.
下表是这些镜子的一些性能指标
a : My own measurement; the official specification is 9.5 degrees
字母a表示我自己地测量值，说明书上是9.5度。
Optical performance光学性能
Angle of view: All glasses are wide angle. I could verify that all three of them have got about 8.5 degrees of real angle, which yields an apparent angle of 60 degrees for the DF and the BPO, and a pretty wide 68 degrees for the Kronos.
视角：这几个都是广角镜子。我能证实所有这三款镜子的真实视角都是8.5度，表现视场DF和BPO是60度，Kronos是68度。
Image sharpness: The BPO is the star! All through almost the entire field, the BPO offers a razor sharp and crisp image. Some degradation is discernible only at the outermost 10% of the field. In the DF and the Kronos, a similar aberration shows up already in the outer 25% of the field. If you think your binocular produces a sharp image, then compare with the BPO and you may reconsider your first impression. Similarly, at the night sky the BPO offers point-like stars throughout most parts of the field. The DF and the Kronos show point-like star images within the inner 60% of the field with a gradually increasing distortion toward the edge. With its large apparent angle of view, however, the Kronos leaves a good overall impression.
图像清晰度：BPO是明星。几乎整个视场，BPO能提供剃刀削过般干净利落的图像。只在视场最靠边的10%能察觉降低。DF和Kronos,在视场靠边的25%就有类似的降低了。如果你认为你的望远镜能提供清晰图像，那就和BPO比较，就会重新考虑开始印象了。类似，夜晚BPO在观星中大部分视场都提供了点状图像，DF和Kronos在中心60%区域提供点状图像，再靠边就逐渐加大变形。当然，Kronos拥有大的表现视场，留下全面的好印象。
Image color: The DF is almost neutral in color, with a very light yellowish tint. The Kronos shows a stronger yellow, but it is grossly outperformed by the BPO with its strong yellow image color. On a scale from 0 to 10, where 0 means neutral and 10 a complete yellow saturation, the DF may get 1 point, the Kronos 3, and the BPO 7 points. Fantao has dismantled the BPO's ocular and found a particular, single yellow lens element. This in fact indicates that probably a special glass type with exotic specifications (e.g. using rare earth or lanthanide additives) had to be employed for the ocular design.
图像颜色：DF几乎是自然色，只有轻微偏黄；Kronos表现更偏黄；但它被BPO的严重偏黄轻松超过。如果定义从0到10的程度，0意味着自然色，10意味着完全黄色，DF得1分，Kronos得3分，BPO得7分。Fantao拆开过BPO的目镜，发现一块特殊的独立黄色透镜，事实说明这种或许有奇异功效的特殊玻璃（举例说,使用稀土或添加了镧系元素）不得不使用在目镜上。
Rectilinear distortion: The BPO does not show any rectilinear distortion, i.e. straight lines appear straight all over the field. Most binoculars intentionally employ a slight amount of pincushion distortion to eliminate the globe effect with the panning binocular. Consequently, the BPO is showing such an effect, i.e. a characteristic convex curvature of the image while panning. Hans Seeger, in his book 'Fernglaeser und Fernrohre', points out that binoculars for naval use were sometimes designed without pincushion distortion, because here it looks particularly odd when the horizon is bending up and down while moving the glass. Therefore it should be pointed out that the presence or absence of pincushion distortion is no indicator for the quality of the binocular, but it reflects a particular design strategy.
直线扭曲：BPO没有任何直线扭曲，就是说，整个视场内看直线显示都是直线。大部分望远镜有意设计了轻微扭曲为了避免移动镜子时产生滚球效应。因此，BPO显示了如此效果，例如，当移动观测时，图像有凸曲面的特性。Hans Seeger在他的书《Fernglaeser und Fernrohre》中提到海军用镜有时设计上没有直线扭曲，因为当移动镜子时，海平线不停的向上向下变换弯曲会看起来很难受。这里需要指出的是枕形畸变的有或无并不标示望远镜的质量，只是反应了特殊设计策略。
Stray light: When there are bright sources of light outside the field of view, some light can enter through the objective lenses and illuminate the inner wall of the tube. Part of this illumination can be reflected into the optical path and enter the eye as stray light, reducing the contrast of the image. Here, the DF performs best, and there is almost no indication for such an effect visible. In the BPO, under certain angles, some stray light can enter, and in the Kronos this effect can become disturbing. It is caused by the somewhat glossy finish of the inner tube. The intensity of the stray light in the Kronos 8x40 is little more than observed earlier in the Kronos 6x30 review, i.e. it is not too bad, but in the present test the competition is tough so that the Kronos is falling a bit behind.
漫射光：当视场外存在光源，部分光线能进入物镜，照亮镜筒内壁。部分光线能被反射进入光路，最后作为漫射光进入眼睛，减少了图像对比度。这里，DF表现最好，几乎没有可见的漫射光迹象；BPO在某些特定角度混进一些些漫射光；Kronos的漫射光作用就比较烦恼了，原因是靠物镜的内部的平滑表面。Kronos 8x40的漫射光程度比早先评测过的Kronos 6x30稍微厉害，就是说，不是最糟糕，但先前评测竞争过于激烈，所以Kronos稍微落后了一些。
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. Here, the Kronos gives a good impression, with very little tendency for ghosting. The DF is similarly immunized through the left tube, but on the right hand side there are reflections on the reticle, which is apparently not well coated. The BPO is prone to ghost images on both sides. It seems that here we have to pay for the extremely complicated eyepiece construction with its numerous air-to-glass transits. Again, the right hand side with its reticle is a little worse.
鬼影：如果，在晚上，一个命令物体（路灯，月亮）进入了视野，在玻璃表面发生反射，能产生光源的多个鬼魂般的影像。这里Kronos表现良好，只有轻微鬼影；DF的左镜筒同样没有，但右镜筒的刻度板有反光，显然刻度板没有很好镀膜；BPO的双筒都有鬼影，这不得不怪罪于极端复杂的目镜的众多玻璃表面，再一次，右边的鬼影现象因为刻度板而更糟糕一点。
Low light performance: The three binoculars perform exactly as expected from their exit pupil diameters: With decreasing day light, the image of the BPO is the first one to turn flat as a result of vanishing surface details. It can be clearly observed how the DF still gives a 3-dimensional impression of the scenery when the BPO just shows some patches of different brightness without any apparent mutual distance relation. This is not a deficiency of the BPO but the natural consequence of its smaller aperture. The Kronos's twilight features come quite close to the DF's, but the fact that the Russian glass is more prone to stray light is of some relevance here: The sky is still brighter than the fields and glare from the tube, projected to the outer edge of the exit pupil, starts entering the eye's pupil which is, at lower light, growing in size. The contrast of the Kronos's image is therefore reduced and this is the main reason why it cannot match the DF's low light performance. With an exit pupil of 5.7 mm, the DF's little residual stray light is gone once it is dark enough for the eye's pupil to surpass this diameter. At the night sky, however, I prefer the Kronos because of its wider apparent angle of view and absence of reticle.
低照明表现：因出瞳直径有区别，这三款镜子如期望的那样表现：随着光线变暗，BPO的图像第一个变得虚弱，结果丧失表面细节。能很清楚注意到DF仍能给出景象的3维表现，而此时当BPO只能显示某些零碎的亮度差异却不能体现距离感，这不是BPO的无能，而是口径较小的自然表现。Kronos的黄昏表现与DF很接近，但俄罗斯的玻璃倾向于抑制漫射光，部分原因是：天空依然比地面亮，眩光照进镜筒，射向出瞳孔径边缘外侧，输入进眼睛，当低照明时，强度随着孔径增大。与DF对比Kronos的图像的因此降级，这是为什么赶不上DF的低照明表现的主要原因。DF拥有5.7mm的出瞳直径，当变的很黑，人眼瞳孔直径超过5.7，DF的一点剩余的漫射光也能忍受。 虽然如此，我更喜欢用Kronos看夜空因为它的更大的表现视野和没有刻度板。 |
|
IP卡
狗仔卡
提升卡
置顶卡
沉默卡
喧嚣卡
显身卡
