barlows与powermates

用barlows加目镜后可增加出瞳距离，但是会使长焦目镜的出瞳距离过长，导致观测受影响，针对这个不良后果，powermates诞生了，powermates的原理和barlows一样，但构造稍许不同，用powermates之后不会影响出瞳距离，但倍数会增加的。

原来用barlows加目镜后会增加出瞳距离,怪不得老容易出现黑影.多谢楼主解决了困忧我的问题.

tv生产的,四片

喔，忘说了，是TV的powermates.

http://www.televue.com/engine/page.asp?ID=42

好像要比barlow好一些，达到其效果，但将其不良之处降低
Powermates
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Concept: While Barlows are powerful tools, the negative element defining them also limits their ability. The simple negative element Barlow increases eyepiece eye-relief. With short focal length eyepieces the effect is negligible. However, on long focal length eyepieces the exit pupil position moves well beyond the designer's intended position, resulting in vignetting with many eyepieces. This is why "Shorty" Barlows in particular, with their strong negative element often vignette and degrade long focus eyepieces. My 4-element form picks up where the Barlow concept can go no further. Powermate™ is a technically universal solution, using a positive field lens to redirect field rays. The result is an exit pupil that stays where the eyepiece designer intended. With freedom from aberrations, greater magnification potential, and compact size, I hope you'll agree Powermate™ raises the standard for image amplification.
- Al Nagler


Al Nagler’s new 4-element concept, continues the tradition of full-field sharpness with optimum aberration control. Like long eye-relief? Retain the eye-relief of long focal length eyepieces, while at high power. Enjoy, for example, the sharpness and comfort of the 32mm Plössl at up to 5 times the power!


Powermate™ vs. Barlow
To understand the Powermate, we must first understand the Barlow lens. Barlows amplify the power of a telescope. They can be considered “focal reducers” for eyepieces, or “focal extenders” for objectives. Terence Dickenson, in his Barlow test report in Sky and Telescope, July 1997, says: “Technology has erased the old objections. A modern Barlow will not degrade your telescope’s optics. Anyone telling you otherwise is using outdated information. Moreover, the highly regarded Nagler eyepieces and their clones have built-in Barlows, ample evidence that the lens is not some detrimental intruder.” Thanks, Terence, for laying the myth of the degrading Barlow to rest.

A high quality Barlow must be properly designed and manufactured in order to avoid compromising a telescope’s color and spherical aberration corrections. The “invisibility” of Tele Vue’s 2-element Barlows has been noted in test reports in the astronomy magazines. However, by the nature of its negative power lens, a Barlow will do more than just increase magnification, regardless of the number of elements.




The diverging rays leaving the Barlow result in moving the exit pupil further out, thereby extending the eye relief. In short to medium focal length eyepieces the change is not noticeable. However, in the case of long focal length eyepieces, the increase can be significant and not without performance consequences.
Vignetting can occur due to the altered ray path, when the eyepiece’s lenses are not large enough in diameter to allow all the rays to make it through. Shorter Barlows, or ones with too much magnification, only exacerbate the problem because the ray path entering the eyepiece is steeper.

We had to go beyond the Barlow concept to achieve the goal of a compact, high power, fully corrected image amplifier. The Powermate™ consists of a negative doublet plus a positive “pupil-correcting” doublet. This 4-element system provides the magnifying function of a Barlow without its limitations by restoring the field rays back to their original direction, as if the Powermate™ were not there. The result is a pure magnification increase.
  

Unique Benefits and Applications for Powermates™
Vignetting, edge field aberrations and pupil movement - all introduced when using Barlows with long focal length eyepieces, are minimized.
Telecentric operation (field rays leave parallel to optical axis, unlike Barlow lenses which diverge rays). This is ideal for Hydrogen-alpha filter use such as with Daystar models.
High performance for image amplification, CCD or film (some of the finest Earth-based planetary imaging is being done with Powermates™ -- see below).
Flexible for visual and imaging with all types of telescopes and eyepieces. Essentially Parfocal, and with nearly constant magnification regardless of image distance behind top surface (except 5x model which increases 1x for every 35mm of image distance increase).
Higher magnifications are possible with high optical performance compared to “doubling up” Barlows.
All will reach parfocal point in star diagonals, except for the 2”, 2x which comes very close.
In addition to full multi-coating, Powermates™ include other Tele Vue special touches such as safety undercuts where practical on the chrome barrel and captive lock screws that can’t fall out, and filter threads. Our 100% QC program at f/4 insures that Powermates™ will add dramatic power (and NOTHING ELSE) to your favorite eyepieces.

If, for example, you own a 24mm Panoptic, you’ll have the power of a 12mm focal length eyepiece with the 2.0x Powermate, 9.6mm with the 2.5x Powermate, a 6mm with the 4x Powermate, or a 4.8mm with the 5x Powermate!



Imaging the Solar System with Powermates™
Some of the finest Solar System images have been made with Powermates. Used singly or stacked, Powermates™ help any scope achieve the long focal-length required to image details on Solar System bodies. The increased image scale allows for imaging without an intervening eyepiece -- like in prime focus photography.





Powermate™ Magnification Chart for Imagers


For astro-imagers, the above chart indicates the magnification for each Powermate™ (2x, 2.5x, 4x & 5x) as a function of distance from the Powermate™ top surface to the imaging surface (CCD or film).

1¼" Powermates: 2.5x & 5x
These models stand less than 3" out of your focuser and the 5x takes 1¼" threaded filters. They are parfocal in ALL 1¼" diagonals and prisms. For this reason, they are highly recommended over standard Barlows for 1¼" diagonals and refractors such as the Tele Vue-60.

The 5x Powermate™ is ideal for long focus CCD and film photography, magnifying about 7.7x. It’s an attractive, high performance alternative to eyepiece projection. The 5x is also perfect for slowing down your scope for Hydrogen-Alpha solar observing.


2" Powermates: 2x & 4x



These Powermates™ are a better choice for 2” diagonals than Barlows, since they are nearly Parfocal. They are threaded for 48mm filters and their performance is excellent with every 1.25” and 2” eyepiece we make (yes, even the 31mm Nagler Type 5!). Both the 2” eyepiece holder and the special 2” flat top adapter use our brass clamp rings for secure operation. And, it also has a very unique feature: you can unscrew the 2” eyepiece housing and screw on a special T-ring adapter for solid, compact attachment of CCD or camera equipment.
Excellent with long eye-relief, 2" eyepieces. Using the 4x model, imagine the quality of a 35mm Panoptic at 8.8mm with 25mm of eye relief! The Powermate™ is NOT a Barlow so the Panoptic-Barlow Interface is not needed! The 2" Powermate™ fits all the way into 2" Star Diagonals, requiring minimal refocus compared to a 2" Barlow.



Note for Dobsonian/Newtonian Owners
When using Tele Vue’s Paracorr coma corrector, the 2.5x or 5x Powermate™ should be inserted into the Paracorr’s 1-1/4” adapter (i.e., between the Paracorr and the eyepiece). For 2x and 4x 2” Powermates, first insert the Powermate™ into the focuser, then the Paracorr into the Powermate.

其实,在实际应用中,优良的巴罗效果与powermates相差不是很大.

据说目视的话，效果普通TV巴罗强于powermate,powermate主要在摄影方面优势很大！！

概念 ： 虽然barlows是强有力的工具，负面因素确定，他们还限制了他们的能力。

The simple negative element Barlow increases eyepiece eye-relief.

简单的消极因素巴卢增加目镜眼救济。

With short focal length eyepieces the effect is negligible.

与短焦距eyepieces的影响是微不足道的。

However, on long focal length eyepieces the exit pupil position moves well beyond the designer's intended position, resulting in vignetting with many eyepieces.

不过，对长焦距eyepieces出境瞳孔位置的动作远远超出了设计者的意图立场，导致装饰图案与许多eyepieces 。

This is why "Shorty" Barlows in particular, with their strong negative element often vignette and degrade long focus eyepieces.

这就是为什么" shorty " barlows ，尤其是与他们强烈的负面因素，往往情景和降解长焦距eyepieces 。

My 4-element form picks up where the Barlow concept can go no further.

我的第4单元形式拿起那里巴卢概念，可以去没有进一步。

Powermate™ is a technically universal solution, using a positive field lens to redirect field rays.

powermate ™是一个在技术上普遍适用的解决办法，用积极的实地镜头转场射线。

The result is an exit pupil that stays where the eyepiece designer intended.

其结果是出瞳说，停留的地方目镜设计者的原意。

With freedom from aberrations, greater magnification potential, and compact size, I hope you'll agree Powermate™ raises the standard for image amplification.

与免于像差，更大的放大潜力，而紧凑尺寸的，我希望你会同意powermate ™提高了标准，影像放大。

- Al Nagler

-铝n agler

Al Nagler’s new 4-element concept, continues the tradition of full-field sharpness with optimum aberration control.

铝nagler的全新4元的概念，仍然是传统的全职场敏锐性与优化畸变控制。

Like long eye-relief?

像长眼救济？

Retain the eye-relief of long focal length eyepieces, while at high power.

保留眼救济的长焦距eyepieces ，而在高功率。

Enjoy, for example, the sharpness and comfort of the 32mm Plössl at up to 5 times the power!

享受，例如，尖锐性和舒适性的32毫米plössl以高达5倍的力量！

Powermate™ vs. Barlow

powermate ™主场迎战巴卢

To understand the Powermate, we must first understand the Barlow lens.

了解powermate ，我们必须先了解巴卢镜头。

Barlows amplify the power of a telescope.

barlows放大功率的望远镜。

They can be considered “focal reducers” for eyepieces, or “focal extenders” for objectives.

它们可以被认为是"焦点减速器" ，为eyepieces ，或"协调人扩"的目标。

Terence Dickenson, in his Barlow test report in Sky and Telescope , July 1997, says: “Technology has erased the old objections.

特伦斯‧狄金森，在他的巴卢测试报告，在天空和望远镜 ， 1997年7月，内容为： "技术已经抹去旧的反对意见。

A modern Barlow will not degrade your telescope’s optics.

现代巴卢不会降低你的望远镜的光学。

Anyone telling you otherwise is using outdated information.

任何人告诉你，否则就是使用过时的资料。

Moreover, the highly regarded Nagler eyepieces and their clones have built-in Barlows, ample evidence that the lens is not some detrimental intruder.” Thanks, Terence, for laying the myth of the degrading Barlow to rest.

此外，备受敬重nagler eyepieces及其无性系有内置式barlows ，充分的证据表明，透镜，是不是有些不利于入侵者。 "谢谢，乐庭，以铺设的神话降解巴卢休息。

A high quality Barlow must be properly designed and manufactured in order to avoid compromising a telescope’s color and spherical aberration corrections.

一个高品质巴卢必须妥善设计及制造，以避免损害望远镜的颜色和球面像差改正。

The “invisibility” of Tele Vue’s 2-element Barlows has been noted in test reports in the astronomy magazines.

在"隐蔽"的远程图书馆新的2元barlows已经注意到，在测试报告，在天文学杂志。

However, by the nature of its negative power lens, a Barlow will do more than just increase magnification, regardless of the number of elements.

不过，由自然的，其消极力量的镜头，一巴卢会做更多工作不仅仅是增加放大，而不论有多少元素。
分歧射线离开巴卢结果在动议出瞳此外，她还指出，从而延长眼救济。

In short to medium focal length eyepieces the change is not noticeable.

在短期至中期焦距eyepieces变化并不显着。

However, in the case of long focal length eyepieces, the increase can be significant and not without performance consequences.

不过，在案件长焦距eyepieces ，所增加，可显着和不无业绩的后果。

Vignetting can occur due to the altered ray path, when the eyepiece’s lenses are not large enough in diameter to allow all the rays to make it through.

装饰图案可以发生是由于蚀变射线路径，当目镜的镜头是不是足够大的直径，让所有的光线，使之通过。

Shorter Barlows, or ones with too much magnification, only exacerbate the problem because the ray path entering the eyepiece is steeper.

短barlows ，或那些太多的放大，不仅会加剧问题，因为射线路径进入目镜是陡峭。

We had to go beyond the Barlow concept to achieve the goal of a compact, high power, fully corrected image amplifier.

我们要超越巴卢概念，以达到这个目标的紧凑型，高功率，充分校正图像放大器。

The Powermate™ consists of a negative doublet plus a positive “pupil-correcting” doublet.

该powermate ™构成负面双另加积极"学生纠正"双重态。

This 4-element system provides the magnifying function of a Barlow without its limitations by restoring the field rays back to their original direction, as if the Powermate™ were not there.

这个四元系统提供放大功能，一间巴卢没有它的局限性，恢复了实地射线回到他们原来的方向，因为如果powermate ™并不存在一样。

The result is a pure magnification increase.

其结果是一个纯粹的放大增加。

  

• Vignetting, edge field aberrations and pupil movement - all introduced when using Barlows with long focal length eyepieces, are minimized.
  装饰图案，边缘场畸变及瞳孔运动-所有介绍时，用b arlows与长焦距e yepieces，最小化。
• Telecentric operation (field rays leave parallel to optical axis, unlike Barlow lenses which diverge rays).
  远心手术（场射线离开平行光轴，不像巴卢镜片，其中发散射线） 。
  This is ideal for Hydrogen-alpha filter use such as with Daystar models.
  这是理想的氢-阿尔法过滤器的使用，如与daystar模式。
• High performance for image amplification, CCD or film (some of the finest Earth-based planetary imaging is being done with Powermates™ -- see below).
  高性能的影像放大，防治荒漠化公约或影片（有些最优秀的扎实基础的行星成像正在做与powermates ™ -见下文） 。
• Flexible for visual and imaging with all types of telescopes and eyepieces.
  灵活的视觉和影像与所有类型的望远镜和eyepieces 。
  Essentially Parfocal, and with nearly constant magnification regardless of image distance behind top surface (except 5x model which increases 1x for every 35mm of image distance increase).
  基本上parfocal ，并与将近不断放大，无论形象背后的距离顶面（除5倍模式，即增加1x的每35毫米的形象距离增加） 。
• Higher magnifications are possible with high optical performance compared to “doubling up” Barlows.
  较高倍率都是可能的高光学性能相比， "倍增行动" barlows 。
• All will reach parfocal point in star diagonals, except for the 2”, 2x which comes very close.
  所有将达到parfocal点，在星对角线，除了对2 " ， 2倍速来非常接近。

In addition to full multi-coating, Powermates™ include other Tele Vue special touches such as safety undercuts where practical on the chrome barrel and captive lock screws that can’t fall out, and filter threads.

除了完整的多媒体涂层， powermates ™包括其他远程图书馆特别涉及诸如安全削弱了地方实际对铬桶和圈养锁螺丝认为不能打折，并过滤线程。

Our 100% QC program at f/4 insures that Powermates™ will add dramatic power (and NOTHING ELSE) to your favorite eyepieces.

我们百分之一百的质量控制程序，在法/四日保险即powermates ™将增加戏剧性的权力（而不是其他） ，以你最喜欢的eyepieces 。

If, for example, you own a 24mm Panoptic, you’ll have the power of a 12mm focal length eyepiece with the 2.0x Powermate, 9.6mm with the 2.5x Powermate, a 6mm with the 4x Powermate, or a 4.8mm with the 5x Powermate!

例如，如果你拥有一个24毫米panoptic ，你将有权力一间12毫米焦距目镜与2.0x powermate ， 9.6毫米与2.5x powermate ，一6毫米与4倍powermate ，或四日0.8毫米与5倍powermate ！
  

Some of the finest Solar System images have been made with Powermates.

有些最优秀的太阳系形象已经同powermates 。

Used singly or stacked, Powermates™ help any scope achieve the long focal-length required to image details on Solar System bodies.

单用或堆放， powermates ™帮助任何范围内实现长期焦距须图像细节，对太阳能系统的机构。

The increased image scale allows for imaging without an intervening eyepiece -- like in prime focus photography.

增加的意象尺度允许成像没有介入目镜-像在首相焦点摄影。

For astro-imagers, the above chart indicates the magnification for each Powermate™ (2x, 2.5x, 4x & 5x) as a function of distance from the Powermate™ top surface to the imaging surface (CCD or film).

为天文探测器，因此，上述图表显示放大率为每powermate ™ （ 2倍速， 2.5x ， 4倍和5倍） ，作为一个函数的距离，从powermate ™顶面到成像面（防治荒漠化公约或影片） 。

1¼" Powermates: 2.5x & 5x

1 ¼ " powermates ： 2.5x ＆ 5倍

                               
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