Eta Carina RGB+Ha for Lum

[turbo_pascale (Rob)]

5 hrs 50 minutes
Saxon 80ED on EQ6Pro

This was a combination of different exposure durations

60s @ -20c for approx. 17 exposures each filter RGBHa (total 1hr 10 mins)
120s @ -20c for 10 exposures each RGBHa (total 1hr 20 mins)
300s @ -20c for 10 exposures each RGBHa (total 3hrs 20mins)

Total exposure time : 5hrs 50mins
Stacked in DSS using "Entropy Weighted Average"

Astrobin link: https://astrob.in/x57ktr/0/

[multiweb (Marc)]

Hi Rob, a little on the red side. Also focus is a bit soft and your corrector needs adjustement, a little further out I reckon. Not much to go. Keep at it.

[turbo_pascale (Rob)]

Thanks Marc,

Definitely need to work on a few things. The whole mono/combining thing is way more messy than I thought. Need to get some more practice!

I’ll take a look at the physical stuff too and see if I can get the spacer a bit closer to right.

Not sure about the focus though. I think it’s pretty close. I suspect part of it is the colour stacking blowing things out. I’ll go check the originals again and see if it’s in the raws or in the processing.

[multiweb (Marc)]

Originally Posted by turbo_pascale

Thanks Marc,

Definitely need to work on a few things. The whole mono/combining thing is way more messy than I thought. Need to get some more practice!

Try to put 50% of Ha in your Red channel and 15% in your blue channel. If you use all your Ha as a lum you get a red/pink salmon look depending on objects.

Originally Posted by turbo_pascale

I’ll take a look at the physical stuff too and see if I can get the spacer a bit closer to right.

You're pretty close now. Try a mill or so out then test again.

Originally Posted by turbo_pascale

Not sure about the focus though. I think it’s pretty close. I suspect part of it is the colour stacking blowing things out. I’ll go check the originals again and see if it’s in the raws or in the processing.

It looked like focus to me in the highres but then again it could be the LUM/Ha blend as stars are always a bit bloated in RGB and tighter in Ha. You focus with a bahtinov mask?

[turbo_pascale (Rob)]

Originally Posted by multiweb

It looked like focus to me in the highres but then again it could be the LUM/Ha blend as stars are always a bit bloated in RGB and tighter in Ha. You focus with a bahtinov mask?

I have a ZWO EAF, but I haven't managed to get the autofocus routines to work properly in SGP just yet (lack of clear nights to just fiddle). High on the priority list of things to do.

I found the best focus by eye, then did shots to measure FWHM and see how good I could get it either side of focus. But that was just a one off, and I wasn't refocussing over and over, nor adjusting on a per filter basis. I think the ZWO filters are pretty par-focal as far as I can tell.

I've attached the processed stacks of Ha and Red (pre colour merging them) from the top right corner. I don't know if the "bloat" in the Red is just the way it is, but the Ha is pretty good.
I qualify that by knowing that this is the corner of the frame too, and the reducer needs some tweaking.

Thoughts?

[multiweb (Marc)]

The red looks good, it's pretty tight. Your corrector doesn't need much tweaking, just a smidge I reckon.

You should get a small bahtinov and refocus as many times as you can, including between filter change. Doesn't take long to do and the results are chalk an cheese. Unless you're remote, then yes go by the numbers and do a Vcurve with focus max or other, but otherwise, manually's the best. Keeping good focus is critical. Often overlooked.

[The_bluester (Paul)]

I personally found it better to get automated focus happening and let SGP (And now Voyager) do it than manually focusing. Focusing by commanding focus moves and looking at the FWHM I found to be just less precise and often really time consuming, Using a mask was better on my SCT but that changes focus so quickly with temperature changes that it really had to be automated!

It should only take you about 20 minutes to get focus runs working in SGP if you read up on the setup process beforehand, I reckon on the SCT it saved me that much imaging time the first night I had it going.