【参赛】連續六天的 M31 + C/2011 L4

攝於英國 LEICESTER
拍攝日期時間: 2013年4月1 - 4月6   ~9pm - 10pm
Camera: Canon 500D
Lens: Day 1-2: EF-85mm & DSS 2x drizzle, f/4, iso 800, 60 seconds
Day 3-6: EF-200mm 2.8L, f/3.5, iso 800, 60 seconds
Mount: HL-1
Filter: Astronomik CLS-ccd filter
叠加张数: 4月1 - 2 ~25 , 4月3-4 ~45, 4月5-6~25
處理軟件: DSS, PixInsight, PS



*M31是用了2012年9月在陰那山拍的M31強化* (這算是"合成"吧...) 請不要拍磚..我不是搞科研什麼..只是唯美至上!!
M31 原圖: https://fbcdn-sphotos-f-a.akamai ... 09_1250573049_n.jpg

The comet should appear to be dimmer each day, however, this phenomenon does not appear on this image because
1) I have used 85mm and DSS 2x drizzle for the first 2 days, hence a rather low S-N ratio, whereas for day 3-5, I have used 200mm 2.8L therefore a rather hgih S-N ratio.
2) I used f/4 for the first 2 days and f/3.5 for day 3-5, this caused the brightness difference
3) PS technique was not so familiar for the first 2 days
4) Number of frames for day 1-2 were <25 and for day 3-4 >40... this provides the high S-N ratio

                               
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NICE !

好看！

顏大,早安

很美！欣赏了!

创意无限。赞一个。

mileszhou 发表于 2013-4-6 09:34

                               
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Great! A question, though; why the comet is getting brighter and brigher? It is supposedly going the ...

You are right! This phenomenon should appear on this photo, however it doesn't. This is caused by several factors: 1) The quality of the photos, as I used 85mm for the first 2 days, the comet has a low S-N ration (stacked with 2x drizzle in DSS) and day3-5 I used 200mm 2.8L hence a better S-N ratio. 2) I used f/4, 1 min, iso 800 for the first 2 days and f/3.5, 1min, iso 800 for day 3-5. This caused the brightness difference, more or less (I should have kept them the same...) 3)  The technique used in photoshop 4) Number of light frames taken per day. I had only <20 frames for the first 2 days because they sink into neighbour's house in a rather short time. I get more number of frames later as the location of L4 changes, hence a better S-N ratio.

mileszhou 发表于 2013-4-6 09:50

                               
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Okay, that explains why, very accurately. Okidoky (not sure if this phrase is used in England); an ...

haha, you are welcome! I do not wish to provide the wrong information~~(Okey-dokey is the correct way to spell it)  {:soso_e112:}

very beautiful！

{:soso_e179:}帅气~

真正的大片

媲美科幻片了亲

羡慕嫉妒狠啊，可悲的贵州，又是半个月阴天，真……

厉害 ！

NB的大片。。。