The sun continue to silent, transparency dropped to 2/10, seeing 2/10. Borg 45ED II, SM40/BF10 for the first shot, PST etalon added forthe second, and finally Cheapy ERF C5 PST etalon for the last shot.
1310 (GMT+8), SM40/BF10:-
1315 (GMT+8), SM40/PST/BF10:-
1325 (GMT+8), Cheapy ERF/C5/BF10:-
I found that even in the Borg setup, internal reflection of the PST etalon is washing out of the contrast, anyway, when you want large aperture, and yet cheap, you will have to live with some problem. Anyway, I'll still try to find solution for it. BTW, I found the objective of the PST has a concave surface on the side facing the etalon, maybe it's the key to stay away from the internal reflection?