2010-07-31 深空及行星攝影工作坊

[社長]

剛於本月初推行的工作坊，本人和Willis便到台灣進行為期七天的拍攝，可說收穫良多。

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我的作品：
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十分欣慰的是，大家都初步掌握了深空拍攝的基本方法，並初有成績：

Willis 的 M8, M20
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David 的 M22, M8
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因天文台預報本週末開始天晴，現初定於明後天晚上舉行深空及行星拍攝工作坊，實習範圍包括：

- 魚骨板及電子調焦
- LVI導星流程、導星鏡操作
- Sky Watcher HEQ5 Pro GOTO alignment
- 赤道儀對極軸方法
- 月面及木星拍攝技巧

各Sky Watcher 赤道儀、LVI 導星器、APM-TMB 折射鏡用戶，若有興趣參與，可以電郵與本人聯絡時間地點。

[Lewis]

明晚要和家人聚餐(科學園)，希望晚些可以來.

但是社長.....
地點是......
請電郵給我........

[社長]

明晚要和家人聚餐(科學園)，希望晚些可以來.

但是社長.....
地點是......
請電郵給我........

good to see you again Lewis.

可能明天臨時才決定，可以到時call Willis知道那裡會合，珊好像也會來的。

[Lewis]

明晚要和家人聚餐(科學園)，希望晚些可以來.

但是社長.....
地點是......
請電郵給我........

good to see you again Lewis.

可能明天臨時才決定，可以到時call Willis知道那裡會合，珊好像也會來的。

無問題.

[willis]

Due to family gathering, Lewis & I arrived Sai Kung at about 00:00 last night. The sky condition was clear when we arrive, but after we setup the equipment, all the clouds started to run around! Together with the annoying moon, it is hard to shot any DSOs! Anyway I tried the North America Nebula, but failed! The P2 has no use in this situation. After that I tuned the target to practice the equipment. I picked the area around Deneb because the Cygnus is taking a bath in the Milky Way. May be I can photo the background color of Milky Way. However, I failed again. Anyway, I practice the focusing & auto guiding. Without the electric Feather Touch focuser, this is what can be done with a stock Equinox dual speed focuser, see focusing.jpg. The focusing star is Vega. About the auto guiding, this is the first time I used the China made 220mm refractor to guide a 500mm. From LVI’s real time guiding curves, I know that there is 1 to 2 pixels error in the guiding scope. This which means there should be some star elongation. Indeed the photo showed this. According to my previous Taiwan trip experience, this may be due to poor balancing or poor cables arrangement in the setup. Perhaps the focal length of the guide scope is not long enough compared with the main scope. The pixel error in the guide scope may be amplified in the main scope’s image. Anyway, the bloody clouds didn’t allow me to find the reason out. The clouds just cover the Cygnus area from time to time and so as my guide star, Deneb. At about 03:00, we gave up. When we just finished packing up all the equipment, it started to rain! We are so lucky!

Equipment:
Equinox 80ED
AstroTech Flattner (Zero Power)
50mm China made refractor of 220mm focal length as guide scope
HEQ5Pro
40D
P2
LVI

[Lewis]

It seems that the moon's effect is very very much. But LVI with large focal length (200mm) guiding lens is O.K.
Maybe next trial is your Skywatcher 1000mm (as I remember you bought a new one for photography of flower) to shot the smaller DSO.

[willis]

It seems that the moon's effect is very very much. But LVI with large focal length (200mm) guiding lens is O.K.
Maybe next trial is your Skywatcher 1000mm (as I remember you bought a new one for photography of flower) to shot the smaller DSO.

That one is a Mak 80/1000. A very small scope for casual observations & flower photography only. Certainly not for DSOs.

[Lewis]

It seems that the moon's effect is very very much. But LVI with large focal length (200mm) guiding lens is O.K.
Maybe next trial is your Skywatcher 1000mm (as I remember you bought a new one for photography of flower) to shot the smaller DSO.

That one is a Mak 80/1000. A very small scope for casual observations & flower photography only. Certainly not for DSOs.

Next time, maybe try my C8 to see the performance.

[willis]

To guide a 2000mm scope is not easy. Maybe we need to work hard & practice more.

[Lewis]

To guide a 2000mm scope is not easy. Maybe we need to work hard & practice more.

Of course, try our best.

[社長]

正如9月份Sky & Telescope測試導星器中也提到一句，導星的實時表現也有其功效。Willis你在台灣對這個感受良多了，其實很多時拍深空時，星點拉線並非單純導星問題，例如導星鏡支撐的剛性問題、平衡、陣風等也是另一因素，而LVI的XY軸實時導星表現就是那麼重要，幫你實時診斷問題，而非事後完成曝光才發現有事。

[社長]

工作坊昨晚繼續進行，我和David到了石澳，可清晰看見天蠍人馬的銀河核心，以及天鵝天區隠約的銀河。

昨晚可說是大豐收了，我和David主力測試兩台自製150口徑牛頓反射鏡，一台是他04年自行磨製，花了數十小時才完成拋物面的。另一台是我指導澳門一所中學磨鏡班，其中一張作品。

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我們昨晚的流程如下，見照片：

- 到埗後首先以澳門中學自製望遠鏡拍攝M8，主鏡焦距924mm、導星鏡為高橋40/240導星鏡，另加2x巴羅配LVI導星

- 之後David用他的APM-LOMO 80/480配TS2平場鏡及LPS V4濾鏡拍攝北美星雲，追蹤簡直是完美的，從沒看過這樣的LVI心電圖，David甚至懷疑LVI是否壞了，嘗試用手遮擋導星鏡，馬上Star Lost，確認沒問題

- 然後用澳門中學自製望遠鏡觀看木星，在Lunt 7-21 Zoom目鏡下表現出色，換上TMB Supermonocentric 6mm，細節進一步提升，到4mm的230x下，對比度有些柔化了。再指向天琴座的Epsilon double double雙雙星，四顆緊密雙星完全分解，之間呈現漆黑天空背景，清晰可見第一衍射環。第一次自製望遠鏡的作品水平如此，絶對理想了。

- 最後我用澳門中學自製望遠鏡觀拍月面及木星、David用他的自製150反射鏡拍月面。

[社長]

初步處理昨日用澳門自製150反射鏡拍攝的作品：

[willis]

The resolution of the DIY scope is quite high! There is coma at the corner. Is it possible to reduce it by coma corrector?

[社長]

The resolution of the DIY scope is quite high! There is coma at the corner. Is it possible to reduce it by coma corrector?

對的，只要肯花時間，自己造的望遠鏡成像可以很高水平的，當晚David用這台鏡配TMB Supermonocentric目鏡看木星及Double Double，都很讚賞這台鏡的水準。

拍深空若配個彗差修正鏡肯定有明顯改善，以這台F6的牛頓鏡計，APS片幅會好些，全片幅就一定要用了。

只是我想表達牛頓鏡的原始美，所以直接拍攝而已。在菲林年代，絶大多數同好用150 F4或F5去拍，也沒有用修正鏡的。

無論如何，用這鏡不是也不應跟頂級APO比較，需要的是一種自信，去欣賞自己的工藝。

[Nebulas]

The resolution of the DIY scope is quite high! There is coma at the corner. Is it possible to reduce it by coma corrector?

對的，只要肯花時間，自己造的望遠鏡成像可以很高水平的，當晚David用這台鏡配TMB Supermonocentric目鏡看木星及Double Double，都很讚賞這台鏡的水準。

拍深空若配個彗差修正鏡肯定有明顯改善，以這台F6的牛頓鏡計，APS片幅會好些，全片幅就一定要用了。

只是我想表達牛頓鏡的原始美，所以直接拍攝而已。在菲林年代，絶大多數同好用150 F4或F5去拍，也沒有用修正鏡的。

無論如何，用這鏡不是也不應跟頂級APO比較，需要的是一種自信，去欣賞自己的工藝。

自己亲手 DO 的东西，再能拍出好片是个人的最高修为了。

[社長]

對，很多人磨鏡，也有很多人拍星，但郤沒有多少人用自己磨製的望遠鏡去拍星。80、90年代還是有些的，現在甚少了。

很希望這些照片能激勵我在澳門這群天文學生。

[Nebulas]

對，很多人磨鏡，也有很多人拍星，但郤沒有多少人用自己磨製的望遠鏡去拍星。80、90年代還是有些的，現在甚少了。

很希望這些照片能激勵我在澳門這群天文學生。

呵呵，我的那几个星图，也希望能尽到微薄之力。

如果社长需要更大尺寸的，我到时候发邮件过来。