The Admiral

I thought that this is a common issue with this filter, irrespective of placement. I can imagine though that the size of the halo might be different for different optical arrangements. Ian

Sorry for double post, glitch in posting. Ian

What sort of exposures/ISO were you using? Ian

What sort of exposures/ISO were you using? Ian

What sort of exposures/ISO were you using? Ian

That is good. I've generally got higher, but less than twice that, which is still pretty reasonable. I use 0.5s guide exposures, were you using 1 sec? Ian

It's worth noting that Altair do this on their expensive filters. https://www.altairastro.com/altair-dualband-ultra-4nm-certified-cmos-filter-2-w-test-report-11468-p.asp You get a wide spectral print-out apparently. Anyone got one and care to comment? Ian

FLO, thanks for that, though may be users aren't aware whether their filter is working well. If it is a bit off wavelength the output might be a bit down, or if the pass band is also wider than it should be, the output might seem good, but at the expense of lower contrast. It's very difficult to tell whether the 400 quid is well spent. And if the manufacturers don't supply bone fide test reports, how are we to know that we are getting what we pay for? I speak as someone who has just one NB filter, and that's dual band. I assume it's up to snuff, but I've no idea whether it should be better. Perhaps I should add that this applies to all brands, not just ASKAR. Ian

I tried using @FLO in my post. Ah, it worked this time! Ian

I'd be interested to know how FLO views the issue of filters not meeting the stated specification, and the practicability of testing those it sells. Ian

Very nice rendition. It has an almost 3D quality to it. Presumably stacked in APP, but what parts did Siril and Affinity play? Ian

With the simplistic notion that luminance is detail rather than colour, I thought I'd try using some luminance data in the mix. Fiddling with the mix parameters of the channel mixer, a completely naive empirical approach on my part, I produced this. I think it's better in that the Flame is not reddened there is more of the dust apparent. Not sure that there is more detail visible in the Ha curtain, and Alnitak isn't so well resolved. I think I have rung as much as I can out of this data. Thanks again for looking. Ian

It is shown on my original images, if you follow the link I gave. It is a light yellowy- pink. Mind you, the colour correction my be a little off I guess. The Ha image, which is also on the link, appears to show the Flame to be quite a strong Ha emitter, and so I expected the nebula to turn more red. No, I don't know exactly know how the Combine RGB tool works exactly. Not as obvious as the PS clearly, but I'm trying to stick with what I have for the moment. Ian

Thanks Steve. I think I know what you mean. If I look at the Ha image I can see a fair bit of detail that doesn't seem to have come through into the blended image. I'm not sure that just adding more of the Ha component will improve that though, as it'll just make more of the image red. When I next get the opportunity I'll tinker some more. Ian

Recently I imaged the Horsehead in wide-band and dual-band with a OSC camera (https://stargazerslounge.com/topic/405602-yet-another-horsehead-nebula/#comment-4341481). I use APP, and the blending was a new venture. This wasn't as straightforward as I'd hoped, as registering the channels was problematic on account of the RGB and Ha images being of rather different sizes (don't ask!), and APP objected using the standard parameters. Anyway, eventually got that sorted. The image represents some 2.5h on Ha, and 3.3h of wide-band, after weeding out the bad ones. ASKAR FRA400 and ASI533MC camera on AM5 mount. ASIAir Plus. WO 50mm guidescope with ASI120MC Wide-band: 100x2m subs; Ha: 50x3m subs, using Optolong L-eXtreme. Here is the result, processed in APP and finished in Lightroom. Thanks for looking. Ian

If I may hijack the thread, can I ask whether this is allied to the mount itself, and therefore not correctable, or is there something in the set-up that causes this? For that matter, does it matter? Ian

It does need guiding. Though, I've no experience with very short focal lengths, but of course it's an expensive mount if you're limited to that. If you use something like an ASIAir then guiding isn't too much of a problem. Ian

That would be useful to me too! Ian

Me too, with a 400mm fl scope sitting on top, and it does seem to be backed up by PHD2 viewer when looking at the guide log. When I've got decent PA of course. I've no experience with long fl / heavy scopes, but it's worth looking at the ZWO mount Facebook site if you can. https://www.facebook.com/groups/zwoasimount/?mibextid=HsNCOg Quite a few folk are using it with larger scopes. Ian

Fascinating. Thanks for posting. Ian

When I want to image the same target another night, I open a sub from the previous imaging, plate solve, and goto. Seems to work. How do you effect that when using the plan mode? Ian

Is there any advantage of plan mode if you only image one target a night and have no automated flats? To me there's no point in doing darks each time when you can take them at any time? You can command meridian flip, re-focus, go to home, and shut down in auto mode. Seems to work for me (or at least, at the moment go to home is dodgy because I've had it not stop at the home position, so I would rather be there!). I don't leave the gear unattended. Ian

Personally, when imaging I just do the lights and sequence just for that. With a cooled set-point camera I do all the darks in a batch and just re-use them. I take flats and dark-flats in the house, after taking the scope off the mount, being careful not to change the focus or camera rotation. The sequencing is up to you, although because there isn't a dark-flats option I call them bias. Ian

Today's broadcast was about superconductivity. What I managed to hear was interesting, and will have to catch up. You have to hand it to Melvin, he's prepared to tackle any obstruse topic. Ian