www.astrocafe.hk

I started DSI since this summer.
http://willisao.blogspot.com/2010/07/my ... 8-m20.html
M8 & M20 are easy targets in the summer. I have seen lots of M42 in Internet. Last night the sky condition is good and enabled me to image my first M42. In the middle of the imaging, LVI complainted several times of loss star! I looked at the sky. The guide star was not covered by clouds. Gosh! The guide scope was fogged! I have no heater. In fact both guide scope & main scope were fogged. I didn’t know when this happened. I have no cleaning kits! This certainly caused loss some contrast & resolution etc. Perhaps there is lots of room for improvement, I am very happy with this image. It marks my first winter DSI this year. The photo is a 100% crop. The new LVI II works nicely & the Astrotech matches the Equinox 80ED quite good. There is a trace of coma at the corner, but not significant.

Equinox 80ED
Astrotech Zero Power flattener
40D
LVI II
350mm guide scope (A modified 9x50 finder scope)
LPS-P2
HEQ5Pro
ISO 800
Dark frame
No flat frame
2x30s, 6x2mins, 2x5mins, 2x10mins = 43mins (Total)

It looks very rich in red colour, Is that the light pollution affect blue colour? It looks a bit violet on my "Monitor", maybe my monitor's problems.

Hi Willis, good shot... it seems AT flattener good match with 80ED. The focusing & guiding are good.

Thanks guys! Here is a darker background version.
To cwlam: I've learnt a lesson this time. I must from time to time check the formation of fog on both guide scope & main scope. The image has been deteriorated. Or I need to buy heater to aviod this disappointing situation! Anyway, the focusing was quite good this time. The stars were quite tight. The tracking was good. In most of the cases, people used to post resized photos, a smaller size. One can cover up the tracking error by doing this. It is no point to say there is no tracking error for a small size photo. Right? Here I posted the full size version & one can see the real performance of the guiding. The stars at the corners were not round. This was coma caused by the flattener. However, the coma was very mirror. For a few hundred dollar flattener, I have no complaint.

Willis, good job!

我很關注你的100%圖，並裁剪了以下一部份作比較，先不談客觀天氣及光害條件給你的限制，我一般判別一幅500、600多mm焦距的M42，會以星雲南側一對相距9角秒的恆星作基準，亦可參考此帖：
viewtopic.php?f=9&t=31

以我個人看，一幅以500、600多mm焦距望遠鏡拍的M42，應以能分解這兩顆星作指標，否則再高談闊論什麼導星系統之間的優劣、調焦方法的不同，都是捉錯用神，某程度上是把問題推到儀器上，不如先把個人基本功練好。很明顯，就算我用第一代LVI也能做到很多人不能達到的導星精度，而且是單張10分鐘曝光的。而你的導星及調焦也發揮了500mm焦段的應有水平，或許若配合防露帶，星點會更銳。

這裡則是11張 x15分鐘曝光的，也是第一代LVI導星的：
viewtopic.php?f=17&t=366

我用五千多元的Sky Watcher EQ5 Pro赤道儀配第一代LVI，承超過10公斤的望遠鏡拍攝，單張曝光10分鐘下的M31，可以放大500%檢視的，但很多人郤迷信一台兩三萬元的赤道儀可以解決問題，但照片郤不見得有改善，甚至往往更差，那問題是在赤道儀、導星器，或個人身上?
viewtopic.php?f=18&t=422
viewtopic.php?f=23&t=427

另外建議任何情況下優先用LPS-P2而非V4，V4是拍這類星雲才發揮奇效的：
viewtopic.php?f=17&t=442

Thanks guys! I agreed with 社長 that:
"我用五千多元的Sky Watcher EQ5 Pro赤道儀配第一代LVI，承超過10公斤的望遠鏡拍攝，單張曝光10分鐘下的M31，可以放大500%檢視的，但很多人郤迷信一台兩三萬元的赤道儀可以解決問題，但照片郤不見得有改善，甚至往往更差，那問題是在赤道儀、導星器，或個人身上?"
Don't say the equipment is cheap or to make a fetish of expensive equipment. As long as the equipment is reasonably good, stunning imges can be produced. Apart from uncontrolled factors, say sky condition etc, the man behind the equipment is the most important factor.

willis 寫:Don't say the equipment is cheap or to make a fetish of expensive equipment. As long as the equipment is reasonably good, stunning imges can be produced. Apart from uncontrolled factors, say sky condition etc, the man behind the equipment is the most important factor.

Astrocafe不時會分享一些神兵利器，什麼大口徑APO、Paramount赤道儀，但我們並沒有被這些名貴器材把自己的基本功埋沒。

這就是一個很好的例子，我們用自己磨的鏡來拍照，鏡身成本就是千多元而已：

viewtopic.php?f=6&t=286