Hi all,
Photo for sharing , details:
Tak E180 ED, P2 + V4 filter , ST2000XM (self guide), L 120s X18, R 120s X2 , G 120sX2 , B120s X3 (RGB 2x2 binning).
Taken on 1 Aug at Yuen Long.
Ben
社長 寫:V4 stacking with a P2 filter is still a V4 filter, may be you lose a few percent transmission at Ha![]()
One thing worth trying is stacking V4 filter with deep red filter that cut off below 650nm, then you got a not-too-narrow band Hydrogen Alpha filter.
http://www.sciencecenter.net/hutech/haimage-v4.htm
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