由 willis » 2010-07-27, 18:57
Henry Wu 寫:是否可請說明此 Filter 的功效
謝謝
I tried both CLS & P2. The P2 is not owned by me. I found that CLS has stronger light pollution reduction power. Both filters block the annoying Na light (589.0 and 589.6 nm)
http://en.wikipedia.org/wiki/Sodium-vapor_lamp. However, the CLS blocks yellow (around 570-590 nm) completely in the spectrum which make it impossible to image those DSO with yellow
http://en.wikipedia.org/wiki/Visible_spectrum. Although there are not much DSO with yellow, Rho Ophiuchi Nebula 星空調色盤 is one of those and is my favor. As u can see from my Ophiuchi Nebula photo, I cannot process out the natural color of Rho Ophiuchi Nebula. This frustrated me a lot. On the other hand P2 block only the annoying Na yellow lines and allow some yellow to pass. So P2 helps a lot in this situation. Well if u have enough money, it is always good to have both. As I mentioned, not many DSOs with yellow, CLS is useful in heavily light polluted area. While P2 is a moderate light pollution filter which enable some yellow to pass.
See these links for the spectrum response of CLS & P2:
http://www.astronomik.com/en/cls/astron ... s_full.png http://www.teleskop-express.de/shop/Bil ... transm.gif
Tak FS60C, APM-LOMO 80/480, APM-TMB 105/650, SW Black Diamond 120ED, Borg 125SD, SW 12" Dobs , Lunt LS35T, Lunt LS80T
TMB Super Mono 4mm, Pentax XO 2.5mm, Baader Planetarium 8-24mm, Nagler (2-4mm, 3-6mm, 13mm), Ethos (3.7mm, 6mm, 10mm), Explore Scientific 100º (14mm, 20mm)
DBK 21, DMK 21, DMK 41, DMK 51, ASI 178MC
Nikon D810A, Canon 5D II, Fujifilm X-T10