王师傅磨制顶级牛反之间的PK

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王师傅磨制顶级牛反之间的PK

文章 wenjia » 週一 28 9月, 2009 11:30

王师傅顶级牛反之间的PK, 附1/20高精度牛反刀口检验视频
本来想等天气好了,再多拍点好图再来PK的
但这个鬼天气让我实在是等不急了

各个镜子的星点测试图早已经出来了,虽然不是那么完美,但也能看到一个大概了

最上面的60ED:不用说了,完美的折射,焦内焦外非常对称,焦点上第二环暗得几乎看不见
这也是为什么完美折射镜反差和锐度高的原因

王师傅150F9抛牛:和完美折射比较,最明显某过于中心遮挡引起的第二环亮度增加,但焦内焦外对称性非常好
和标准的有遮挡的图非常接近,王师傅曾经测得此镜1/20的精度,现在看来名不虚传!!

王师傅150F9球反:焦内焦外对称性没有抛牛的好,但焦点上的艾利斑和抛牛比似乎第二环似乎更暗,这让我实在迷糊了一阵时间,第二环的亮度意味着球差的大小,焦内焦外不对称也意味着有球差,如此对称的抛牛的艾利斑的第二环居然比球反的还要亮, 百思不得其解。
后来仔细回想和经过王师傅提醒终于找到了合理的解释:
1.拍的时候球反的星点亮度要低,最高值230,而抛牛的星点亮度已经255了,已经有点过饱和了。
2.抛牛的副镜座做的有点厚,直径达到40mm,而球反的36-37mm,遮挡要小

王师傅150F5抛牛:F5的虽然比F9的只短了一半,但调试的难度确不止高出一倍,要调得和150F9那么好看真的要下一翻苦功夫。而且如果完全没有调过,不知道什么是光轴正的牛反的新手的话,更加会无可适从,所以新手想用牛反的话,个人还是推荐长焦的。从150F5的星点看,象散更加明显,对称性比F9球反要好,抛物面F9略差,所以精度肯定在球反之上,但现在看来主要矛盾变成了光轴的调试。象散应该是光轴不正引起的。星点艾利斑看的话也还过得去,之前拍过木星,效果还可以。

3种牛反的星点图都已经一个个分析,现在该总结了:
能拥有一支完美的反射镜,这是每个人都希望的。购买的时候总是希望精度有多高多高,但很多人却没有要求自己技术有多高。送一句话给想玩却还没有拿定主义的朋友:牛反玩的就是技术活,投入越多,获得越多。一台没能发挥出性能的牛反,不如一台的小折射。对精度的追求应该和技术的追求同步上,虽然150F9抛牛拥有最高的精度,但我用过几次还没有哪次超过了150F9球反,那一点点差距完全感觉不到,只能通过焦内焦外的图看出来。所以建议大部分爱好者判断一具望远镜的好坏还是看艾利斑,只要艾利斑清晰可见,基本上就不是太差的镜子。眼睛比CCD的感光度要宽,加之视宁度的影响,所以大镜子看亮星很多时候会看到很多圈不停晃啊晃的。所以还是建议用摄像头来拍,中心的阀值不要超过255,200-255之间最好,这样能保持足够的亮度又不饱和。
一点心得,希望能成为迎接国庆中秋送给大家的礼物




王师傅的技术也在星点测试中得到了最好的证明
王师傅的抛物面检测是通过平面镜补偿来检测的,因为检测用的平面镜也是王师傅自己磨的,而没有经过专门机构的检测和鉴定,所以很多人都质疑王师傅用的平面镜的精度,如果平面镜不平,怎么能磨出好的抛物面呢?包括我,一样质疑过
但现在看来,质疑和担心是多余的,王师傅通过这套检验设备估算出牛反的精度,通过星点测试完全得以证明,反过来亦证明了王师傅的平面镜的精度
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Wah!!
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文章 Wah!! » 週一 28 9月, 2009 11:37

150F9 拋物鏡的影像很完美對稱!
一定是行星攝影的利器!

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Re: 王师傅磨制顶级牛反之间的PK

文章 Chanlunlun » 週一 28 9月, 2009 13:33

wenjia 寫: 最上面的60ED:不用说了,完美的折射,焦内焦外非常对称,焦点上第二环暗得几乎看不见
这也是为什么完美折射镜反差和锐度高的原因
Judging from the star test diagram, this ED refractor shows slightly undercorrection. Not entirely perfect.
wenjia 寫:[王师傅150F9抛牛:和完美折射比较,最明显某过于中心遮挡引起的第二环亮度增加,但焦内焦外对称性非常好
和标准的有遮挡的图非常接近,王师傅曾经测得此镜1/20的精度,现在看来名不虚传!!

The mirror still sffers from very slightly undercorrection. Judging from the in-focus and out-focus diagram, the P.V. error on mirror surface should be around 1/10 to 1/12 wave. Excellent indeed, but, unfortunately, still not up to 1/20 wave P.V. mirror surface error.

In addition,( I am not quite sure ), judging from the in-focus and out-focus diagram, the mirror also suffers from slight distorsion from the three clamps at the mirror edge. This is not figuring error, but the mountong error of mirror.
wenjia 寫:王师傅150F5抛牛:F5的虽然比F9的只短了一半,但调试的难度确不止高出一倍,要调得和150F9那么好看真的要下一翻苦功夫。而且如果完全没有调过,不知道什么是光轴正的牛反的新手的话,更加会无可适从,所以新手想用牛反的话,个人还是推荐长焦的。从150F5的星点看,象散更加明显,对称性比F9球反要好,抛物面F9略差,所以精度肯定在球反之上,但现在看来主要矛盾变成了光轴的调试。象散应该是光轴不正引起的。星点艾利斑看的话也还过得去,之前拍过木星,效果还可以。
This mirror suffers from astigmatism, as easily judged by the diagram. I belief that this might be due to too thin of mirror blank and the use of clamp-mounting method. Try to use double sided foam tape, this will eliminate such problem.


Undoubtedly Mr. Solodin is one of the best mirror maker inside China. All his mirrors are believed to be well made and more than adequately perform under starry sky, no matter under wide angle deep sky scrutiny or high power planetary observation. But to make a 1/20 wave P.V. mirror is by no means easy. I firmly belief that there must be some within the ownership of Mr. Solodin, but not including the ones presented here.

Best regards
Chan Yuk Lun

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註冊時間: 週二 21 10月, 2008 17:02

Re: 王师傅磨制顶级牛反之间的PK

文章 wenjia » 週一 28 9月, 2009 14:03

陈先生 你好 谢谢你的评论
Chanlunlun 寫: Judging from the star test diagram, this ED refractor shows slightly undercorrection. Not entirely perfect.
这个ED镜子我测试的时候 是晶华3x巴罗+延长管测试的 光轴也稍微有点不正
是否巴罗引入误差 也不好说 但我觉得对于一般的爱好者来说 是比较完美的了 波前误差(wave PV)应该1/10以上

Chanlunlun 寫: The mirror still sffers from very slightly undercorrection. Judging from the in-focus and out-focus diagram, the P.V. error on mirror surface should be around 1/10 to 1/12 wave. Excellent indeed, but, unfortunately, still not up to 1/20 wave P.V. mirror surface error.

In addition,( I am not quite sure ), judging from the in-focus and out-focus diagram, the mirror also suffers from slight distorsion from the three clamps at the mirror edge. This is not figuring error, but the mountong error of mirror.
陈先生看星点图好像很少考虑副镜引入的不确定性因素
但我在测试的过程中 却往往发现很多误差都是副镜引入的
镜子装配采用的是最简单的3点固定 但三个爪都没有靠上主镜 而主要用力是从旁边 我在周边一圈一圈的垫一些植绒 直到不晃动为止 3个爪主要是防止主镜倒出 不起固定作用
另外:王师傅说的主镜镜子是表面精度(surface PV 我们这边习惯用表面精度)而不是陈先生说的波前误差(wave PV), 所以王师傅说的1/20 也就是1/10的 wave PV应该和陈先生估算的值还是很接近的。
Chanlunlun 寫: This mirror suffers from astigmatism, as easily judged by the diagram. I belief that this might be due to too thin of mirror blank and the use of clamp-mounting method. Try to use double sided foam tape, this will eliminate such problem.


Undoubtedly Mr. Solodin is one of the best mirror maker inside China. All his mirrors are believed to be well made and more than adequately perform under starry sky, no matter under wide angle deep sky scrutiny or high power planetary observation. But to make a 1/20 wave P.V. mirror is by no means easy. I firmly belief that there must be some within the ownership of Mr. Solodin, but not including the ones presented here.

Best regards
Chan Yuk Lun
150F5这个可以肯定的是副镜的问题,没有装配很准 我没有下太多功夫
而且F5比F9也更加难调

谢谢你的褒奖 1/10 wave PV相信对于所有爱好者都能够满足了 呵呵

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Re: 王师傅磨制顶级牛反之间的PK

文章 Chanlunlun » 週一 28 9月, 2009 14:35

wenjia 寫:陈先生 你好 谢谢你的评论
Chanlunlun 寫: Judging from the star test diagram, this ED refractor shows slightly undercorrection. Not entirely perfect.
这个ED镜子我测试的时候 是晶华3x巴罗+延长管测试的 光轴也稍微有点不正
是否巴罗引入误差 也不好说 但我觉得对于一般的爱好者来说 是比较完美的了 波前误差(wave PV)应该1/10以上

Chanlunlun 寫: The mirror still sffers from very slightly undercorrection. Judging from the in-focus and out-focus diagram, the P.V. error on mirror surface should be around 1/10 to 1/12 wave. Excellent indeed, but, unfortunately, still not up to 1/20 wave P.V. mirror surface error.

In addition,( I am not quite sure ), judging from the in-focus and out-focus diagram, the mirror also suffers from slight distorsion from the three clamps at the mirror edge. This is not figuring error, but the mountong error of mirror.
陈先生看星点图好像很少考虑副镜引入的不确定性因素
但我在测试的过程中 却往往发现很多误差都是副镜引入的
镜子装配采用的是最简单的3点固定 但三个爪都没有靠上主镜 而主要用力是从旁边 我在周边一圈一圈的垫一些植绒 直到不晃动为止 3个爪主要是防止主镜倒出 不起固定作用
另外:王师傅说的主镜镜子是表面精度(surface PV 我们这边习惯用表面精度)而不是陈先生说的波前误差(wave PV), 所以王师傅说的1/20 也就是1/10的 wave PV应该和陈先生估算的值还是很接近的。
Chanlunlun 寫: This mirror suffers from astigmatism, as easily judged by the diagram. I belief that this might be due to too thin of mirror blank and the use of clamp-mounting method. Try to use double sided foam tape, this will eliminate such problem.


Undoubtedly Mr. Solodin is one of the best mirror maker inside China. All his mirrors are believed to be well made and more than adequately perform under starry sky, no matter under wide angle deep sky scrutiny or high power planetary observation. But to make a 1/20 wave P.V. mirror is by no means easy. I firmly belief that there must be some within the ownership of Mr. Solodin, but not including the ones presented here.

Best regards
Chan Yuk Lun
150F5这个可以肯定的是副镜的问题,没有装配很准 我没有下太多功夫
而且F5比F9也更加难调

谢谢你的褒奖 1/10 wave PV相信对于所有爱好者都能够满足了 呵呵
Dear Mr. Wenjii,

Thanks for your prompt reply. Please also note that

1. All the error I refer to is MIRROR SURFACE ERROR, not wavefront error.

2. The effect of less than perfect diagonal mirror will usually result an astigmatic but not undercorrected star image. So the mirror still suffers from an undercorrection and I judge that is about 1/10 to 1/12 wave ON MIRROR SURFACE. ( that is 1/5 to 1/6 P.V. on wavefront error ). An excellent mirror indeed.


I star tested hundreds of mirrors and I know exactly what a 1/10 wave P.V. Wavefront Error (that is 1/20 wave P.V. on mirror surface ) looks like. I still firmly belief that Mr. Solodin possesses some 1/20 wave P.V. mirror ( I mean 1/10 wave P.V. on wavefront error ) under his collection but he is so careful not to let them out at the moment.

Among all my tested mirrors only very very few approaches 1/10 wave P.V. wavefront error ( 1/20 wave surface error ). Anyone who is lucky enough to have such possession will be a life-time treasure.

Finally I do agree with you - a 1/8 wave and a 1/20 wave P.V. mirror 9 I mean surface error ) perform much the same under average sky condition. Even under really steady air a 1/20 wave mirror will not that far outperform a 1/8 wave mirror. The collimation of the mirror, however, gives the dominate factor upon how good performance a Newtonian is. So, the using of a Newtonian, especially for those of big aperture ( 20 inches or more ), requires expertize technique.

Best regards
Chan Yuk Lun

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文章 MANDII » 週一 28 9月, 2009 15:41

两位长篇大论,5知握麦 [搞自閉]

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Re: 王师傅磨制顶级牛反之间的PK

文章 wenjia » 週一 28 9月, 2009 16:26

Chanlunlun 寫: Dear Mr. Wenjii,

Thanks for your prompt reply. Please also note that

1. All the error I refer to is MIRROR SURFACE ERROR, not wavefront error.

2. The effect of less than perfect diagonal mirror will usually result an astigmatic but not undercorrected star image. So the mirror still suffers from an undercorrection and I judge that is about 1/10 to 1/12 wave ON MIRROR SURFACE. ( that is 1/5 to 1/6 P.V. on wavefront error ). An excellent mirror indeed.


I star tested hundreds of mirrors and I know exactly what a 1/10 wave P.V. Wavefront Error (that is 1/20 wave P.V. on mirror surface ) looks like. I still firmly belief that Mr. Solodin possesses some 1/20 wave P.V. mirror ( I mean 1/10 wave P.V. on wavefront error ) under his collection but he is so careful not to let them out at the moment.

Among all my tested mirrors only very very few approaches 1/10 wave P.V. wavefront error ( 1/20 wave surface error ). Anyone who is lucky enough to have such possession will be a life-time treasure.
非常抱歉陈先生
我英语水平不是太好 一看到wave PV就以为是wave front PV了
误解了

下面是我用软件Aberrator模拟的一个焦内焦外的图
不管这个球差属于低级球差还是高级球差 1/5的波前球差 焦内焦外区别还是很明显的,陈先生是不是低估了自己镜子的精度?

还有
如果说150F9抛物面那个是1/5到1/6的波前精度
那么150F9球面那个是多少精度呢?
球面镜的检测比抛物面容易多了 只用刀口仪即可
不存在任何检测上的问题 王师傅检测得到的数据是接近理想球面 1/10
和标准的F9抛物面比也是 差不多1/5波前误差
从焦内焦外图看 球面和抛物面的差别还是很大的
Chanlunlun 寫: Finally I do agree with you - a 1/8 wave and a 1/20 wave P.V. mirror 9 I mean surface error ) perform much the same under average sky condition. Even under really steady air a 1/20 wave mirror will not that far outperform a 1/8 wave mirror. The collimation of the mirror, however, gives the dominate factor upon how good performance a Newtonian is. So, the using of a Newtonian, especially for those of big aperture ( 20 inches or more ), requires expertize technique.

Best regards
Chan Yuk Lun
陈先生说得很好
这个是我之前150F9球反拍的图 足以证明这一点
圖檔
圖檔
圖檔

圖檔圖檔
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文章 Wah!! » 週二 29 9月, 2009 12:05

焦點前後的影像如此對稱, 究竟靠什么來估計或計算它的精度是 1/5 波面誤差?

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