PST-130 image

[Wah!!]

http://www.astronomie.be/dodi/sun20060805.html

[Cindy]

毛茸茸毛茸茸...

[Wah!!]

每條毛都有地球直徑咁長架!

[universe24]

Wah!!几时整返支来搞搞啊？

[Wah!!]

我都未有一支好的較大口徑折射鏡, 所以未打算拆 PST 住呀.

[Wah!!]

http://www.astronomie.be/dodi/sha20060807bs.jpg

[universe24]

睇到D相影成这样都仲忍得手...佩服...我已经心动动啦。用支质素无那么好的折射镜会点？

[Wah!!]

視乎"质素无那么好"的定義喇.
若是像散、彗差等, 加濾鏡也不會見得好.
若純粹是色差, 相信加濾鏡後效果會不錯.

長焦傾軸牛頓鏡加 barlow 可能都用得.

這種改裝, 首先要有一塊大的 ERF (Energy Rejection Filter).
價錢也很貴的呢.

[HK.Raymond.Tse]

Wah,

The Cool ERF is an optically flat (1/10 lamda) Schott glass 610 substrate plus IR Cut coating.

Can we just use Baader solar film + IR Cut filter to replace the expensive C-ERF ?

Raymond

[Wah!!]

Of course not~

Baader solarfilm will cut all spectrum to 1/100000
ERF will keep H-a to 9x%

[noodle]

Hi Wah!!
Can u show me the link to info. about the transmittance of the Baader C-ERF. I can't find any info. about C-erf except the "Price "

[Wah!!]

This is a website shows how a H-a solar filter works.

http://translate.google.com/translate?u ... en&ie=UTF8

[sn-10]

one should be very careful about the difference between etalon and a pure ha filter.

[Wah!!]

More info here:
http://www.alpineastro.com/Solar_Observ ... afeUse.doc

[Wah!!]

Some more info:
http://www.cloudynights.com/ubbthreads/ ... ll/fpart/1
http://www.sungazer.net/erf.html