滿月下的M57

[CK]

LRGB 各15 min 共 1小時，由於M57 夠光，我減去背境光後，依然不俗。

ck

[Wah!]

其實點解藍色唔使曝耐d光呢?聽聞CCD的藍光感光會無咁好架?
呢張相同上次個張都好似少左藍色,變得偏綠.
不過Detail就process得現過上次第一張.

[Wah!]

剛剛比較返佢的detail係少過上次,但係滿月影成咁,即係話香港光害都可以影到DSO啦!!!!!!!

[CK]

多D Detail，又點睇

[CK]

剛剛比較返佢的detail係少過上次,但係滿月影成咁,即係話香港光害都可以影到DSO啦!!!!!!!

D object 夠光就得，如果影暗野，都係無光害環境著數！！

ck

[CK]

其實點解藍色唔使曝耐d光呢?聽聞CCD的藍光感光會無咁好架?
呢張相同上次個張都好似少左藍色,變得偏綠.
不過Detail就process得現過上次第一張.

正常而言這是對，但這張M57 有點不同，由於在滿月下拍，所以刻意曝光過度(8.8 等 1小時曝光)，在執相時就有好大空間，慢慢調D Detail，而B Channel 在執相時手鬆D 就足夠補償。

不過偏綠的主因，在三色合成後，我覺得背境星點偏藍，而減小藍光比例，星雲就成綠色，不過我以前用18吋鏡過，我記得M57是帶綠色，不知是否主觀印像？

ck

[Subaru]

不過我以前用18吋鏡過，我記得M57是帶綠色，不知是否主觀印像？

ck

因為人眼對綠色最敏感, 所以用大鏡睇M57的綠色部份(主要是Oxygen的emission line)比較易察覺到. 其他的顏色如紅及藍就比較難察覺.

有機會真係想見識嚇大鏡睇疊士佳的知味.

[Wah!]

多D Detail，又點睇

呢張好左好多!除央星旁邊個粒星,同理環上個兩粒星都出左來喇!
會唔會影多幾次,最後sum左前後咁多張,睇下影唔到到M57外圍的氣體呢?

[HK.Raymond.Tse]

I believe we can still take good CCD or imaging in HK during bright moon. The question is whether we have such good imaging equipments.

On 09-08-2003 (12th day of lunar month), I could still vaguely see a tiny M57 in my 4-inch refractor despite the bright moon.

[訪客]

Very nice.
After seeing your images, I am to itchy to obtain a filter wheel for colour imaging!
Have you try to use OIII filter?
Thanks for sharing your images.

Eddie Chan

[CK]

I believe we can still take good CCD or imaging in HK during bright moon. The question is whether we have such good imaging equipments.

On 09-08-2003 (12th day of lunar month), I could still vaguely see a tiny M57 in my 4-inch refractor despite the bright moon.

可使用不同的濾鏡作輔助，行星狀星雲用 O III，星雲用narrow band，再用大口徑鏡補償濾鏡做成的光度損失。

ck

[CK]

Very nice.
After seeing your images, I am to itchy to obtain a filter wheel for colour imaging!
Have you try to use OIII filter?
Thanks for sharing your images.

Eddie Chan

Eddie 兄，O III filter 可大大提高分解度，以下為 OIII 影像，以供參考。