On my mono setup (ASI294mm) I originally used all the legacy 1.25" filters that I had/have, Astronomik IIc for LRGB and a mixture of Astronomik, Baader and Astrodon True-Balance for NB (Hb, Ha and OIII). Never actually had any SII filter previously.
The LRGB set failed spectacularly from the get go with my f/4 optics and was soon replaced by a much better performing set of 31mm ZWOs. The performance of the NB was ok, except for vignetting which was troublesome for both the OIII and to a lesser extent the Hb filter too. Ha was ok-eish. Still, the Hb BW is 12nm, the Ha is 6.5nm and the Astrodon is 6nm. Good but not great from my circumstances (B7 with low transparency year around) so I was looking for a filter set that would be tighter in bandwidth, had the same optical thickness and less clipping of the marginal rays and included the Sulfur filter.
Looking around for 31 mm unmounted filter set they are rarer than hen's teeth and just as expensive as they larger cousins the 36 mm one. Finally, after at considerable amount of research, I landed on this, to me unheard of, manufacturer of the Far East. The asking price was ridiculously low even for a 1.25" set (£83 shipped inclusive of taxes). They don't sell 31mm but the clear aperture of 26mm would have been a step forward compared with the 23mm of the Astrodon one and on par with the Baader's Ha.
The filters arrived within a fortnight and promptly went into the FW. Luckily I had a break in the weather which allowed a test in between weather fronts. Obviously clouds soon enough rolled in and I had to cut short on the SII exposures. Having ask for a SII rich target here the consensus was that for my location and time of the year a bright enough subject would be the the Heart Nebula and I went for despite the restricted size of the FOV, but again it was a test. After a week of clouds and inclement weather I had another break which allowed me to capture enough of the SII signal (but not enough of the OIII, sadly). The images below show the main starless masters with just auto-stretch applied and nothing else:
Ha: 20x180s
OIII: 37x180
SII: 60x180s
Now, IC1805 isn't really OIII rich so I didn't expect a lot of signal except for NGC895. SII is new to me but given the transparency conditions I'm pretty chuffed on how it turned out.
On the basis of these 3 images I created a Forrax palette SHO rendering (with further curves to control background and mid-tone levels. No BXT was used but NXT was, to reduce the noise to a presentable level.
Overall I'm please with how things turned out and I cannot wait for a good chance to test the filter set on Alnitak.
The LRGB set failed spectacularly from the get go with my f/4 optics and was soon replaced by a much better performing set of 31mm ZWOs. The performance of the NB was ok, except for vignetting which was troublesome for both the OIII and to a lesser extent the Hb filter too. Ha was ok-eish. Still, the Hb BW is 12nm, the Ha is 6.5nm and the Astrodon is 6nm. Good but not great from my circumstances (B7 with low transparency year around) so I was looking for a filter set that would be tighter in bandwidth, had the same optical thickness and less clipping of the marginal rays and included the Sulfur filter.
Looking around for 31 mm unmounted filter set they are rarer than hen's teeth and just as expensive as they larger cousins the 36 mm one. Finally, after at considerable amount of research, I landed on this, to me unheard of, manufacturer of the Far East. The asking price was ridiculously low even for a 1.25" set (£83 shipped inclusive of taxes). They don't sell 31mm but the clear aperture of 26mm would have been a step forward compared with the 23mm of the Astrodon one and on par with the Baader's Ha.
The filters arrived within a fortnight and promptly went into the FW. Luckily I had a break in the weather which allowed a test in between weather fronts. Obviously clouds soon enough rolled in and I had to cut short on the SII exposures. Having ask for a SII rich target here the consensus was that for my location and time of the year a bright enough subject would be the the Heart Nebula and I went for despite the restricted size of the FOV, but again it was a test. After a week of clouds and inclement weather I had another break which allowed me to capture enough of the SII signal (but not enough of the OIII, sadly). The images below show the main starless masters with just auto-stretch applied and nothing else:
Ha: 20x180s
OIII: 37x180
SII: 60x180s
Now, IC1805 isn't really OIII rich so I didn't expect a lot of signal except for NGC895. SII is new to me but given the transparency conditions I'm pretty chuffed on how it turned out.
On the basis of these 3 images I created a Forrax palette SHO rendering (with further curves to control background and mid-tone levels. No BXT was used but NXT was, to reduce the noise to a presentable level.
Overall I'm please with how things turned out and I cannot wait for a good chance to test the filter set on Alnitak.
Safe to say I will be swapping these out with Antlia or Scorpio filters as soon as I can.