Going ok for now... got 15x4m OIII, done a preliminary stack and looks good

Got Ha running now, also 4m, which I'll leave until around 00:10 to get 15 subs also. Then Ill drop in the SII filter and hope it's parfocal enough given it's not too different in wavelength from Ha, and astronomik filters are supposed to be parfocal, but they don't say down to what f ratio that applies.
My polar alignment still suck, as I'm getting some pixels of drift per sub, but the 300mm f/2.8 I'm using isn't one for pin sharp stars anyway so that'll mask it. The apparent detail already blows away anything I've done with the 135/2. And the drift acts as my dither. Sorted.
I might have to use flats since a preliminary DBE didn't get rid of the gradient adequately. My subject is the veil again, and that has faint nebulosity all over the place which is probably confusing DBE enough to be a problem. But the system definitely wasn't parfocal between OIII and Ha, so the focus needed a slight tweak. Oh, I think I could use a bathinov mask. Can't see naff all in live view in Ha at f/2.8. So slow... even f/2 was borderline.
Once I got the Ha in, I might do a preliminary output with Ha=red, OII=blue and synthetic green as that palette worked really well last time.
Haven't checked moonrise times yet, but if I really push it after I get SII, I might try the ST120 on the bubble nebula in RGB if I can find it...