Moving from broadband to narrowband...

[TiffsAndAstro]

34 minutes ago, 900SL said:

It ;looks about right, I use 3 minutes. It's not a lot, you are cutting out a lot of light and remember that Oiii signal is usually weaker than Ha

yeah i was wondering if there is a complimentary filter something + Oiii, so that could make up some of the Oiii weaker signal on second run but need to look into that. 

[TiffsAndAstro]

43 minutes ago, 900SL said:

I use two zwo 2" filter holders, they slot into the filter drawer and you can buy them separately

Make sure you check and get the right sizes

https://www.firstlightoptics.com/zwo-accessories/zwo-spare-extra-2-filter-holder-for-m42m54eosnikon-filter-drawers.html

When extracted I keep the spare one in a soft plastic wallet

yeah i ordered a spare one of those from svbony with my filter for my svbony filter drawer. looks very similar, but dunno if identical. i'd like a holder to hold one or maybe two of them

[900SL]

32 minutes ago, TiffsAndAstro said:

yeah i was wondering if there is a complimentary filter something + Oiii, so that could make up some of the Oiii weaker signal on second run but need to look into that. 

Askar do a Sii/Oiii filter but TBH I'd just pile up the Ha/Oiii on 3 min exposures. Important to get the Oiii out of the noise. 

You can channel split in Siril (there's a script) and use the 'linear match' tool to match the Oiii stack to Ha

[TiffsAndAstro]

3 hours ago, iantaylor2uk said:

I tend to use 2-3 minutes subs when using my L-Enhance filter (as opposed to 30-60 secs for simple IR/UV filter). I would also look at increasing your gain value since you're less likely to saturate stars, and you get lower noise at higher gain 

Apologies if this is repeat post, I thought I'd replied

I'm going to stick with unity gain = 101 to start with, and will up my exposure times if needed.

but with clouds and satellites and such, I think 5 and 10 minutes sub times are out, so might need to up gain if 3 min subs seem under exposed.

does that seem like a decent plan?

 

[TiffsAndAstro]

17 minutes ago, 900SL said:

Askar do a Sii/Oiii filter but TBH I'd just pile up the Ha/Oiii on 3 min exposures. Important to get the Oiii out of the noise. 

You can channel split in Siril (there's a script) and use the 'linear match' tool to match the Oiii stack to Ha

Er not seen the linear match tool. All I've done in my experiments with fake hoo was ha to red channel and Oiii in green and blue channels. Doesn't look great but then it wasn't real ha oiii.

Need to look at linear match in siril. It sounds like what the normalisation feature in pixinsight does?

[900SL]

8 minutes ago, TiffsAndAstro said:

Er not seen the linear match tool. All I've done in my experiments with fake hoo was ha to red channel and Oiii in green and blue channels. Doesn't look great but then it wasn't real ha oiii.

Need to look at linear match in siril. It sounds like what the normalisation feature in pixinsight does?

Yes, it's a while since I did dual narrowband but from memory:

Use the 'OSC extract Ha/Oiii' script to create two (mono I think) files for Ha and Oiii from the dual narrowband stack

Do background extraction both files

Do star extraction if required on both files separately on the linear file (I think.. )

Do linear match on Oiii file using the Ha file as the reference. This matches the background ADU of both files

Not sure what I did next, maybe process each file first , then Pixel math or RGB composition to combine both files into an RGB image

There's guidance on line

 

 

 

Edited Tuesday at 12:21 by 900SL

[TiffsAndAstro]

31 minutes ago, 900SL said:

Yes, it's a while since I did dual narrowband but from memory:

Use the 'OSC extract Ha/Oiii' script to create two (mono I think) files for Ha and Oiii from the dual narrowband stack

Do background extraction both files

Do star extraction if required on both files separately on the linear file (I think.. )

Do linear match on Oiii file using the Ha file as the reference. This matches the background ADU of both files

Not sure what I did next, maybe process each file first , then Pixel math or RGB composition to combine both files into an RGB image

There's guidance on line

 

 

 

cheers for all that. all i've seen so far is in the siril guide and its not much, but im sure i'll find more if i need any after your tutorial  

 i've already saved your tutorial to a text file for handy reference.  im fairly sure this is a tool i that was only in pixinsight so im very happy to find siril has it

Edited Tuesday at 12:52 by TiffsAndAstro

[Elp]

You could just extract the red, green and blue channels separately in gimp or PS. Simple.

[TiffsAndAstro]

40 minutes ago, Elp said:

You could just extract the red, green and blue channels separately in gimp or PS. Simple.

Siril also does this, but on a stacked result only.

[Elp]

But that's what you want, you extract/split the channels after stacking.

[TiffsAndAstro]

24 minutes ago, Elp said:

But that's what you want, you extract/split the channels after stacking.

Sure but I have the other siril stacking option to stack into separate Ha and Oiii results.

I literally have no idea the pros and cons of each, other than one is via a stacking script and other works on final stacked results.

I'm sure I'll try both

[Elp]

Up to you how you go about it. When doing OSC I usually just process the stack as is (with starless of course), don't split channels or anything.

[TiffsAndAstro]

3 minutes ago, Elp said:

Up to you how you go about it. When doing OSC I usually just process the stack as is (with starless of course), don't split channels or anything.

Pretty certain this will be my first option, but no harm me having other options to compare results to

hopefully my 1970s orange brown colour scheme will be a thing of the past

Edited Tuesday at 14:33 by TiffsAndAstro

[Elp]

The main thing will be incorrect star colour but you already know to image separately and replace these after.

[TiffsAndAstro]

7 minutes ago, Elp said:

The main thing will be incorrect star colour but you already know to image separately and replace these after.

Yeah been testing that.

How much I need time I need to grab RGB stars I'll find out. Starting at 30 minutes I think

[TiffsAndAstro]

I'm on M16 right now. Had to polar align a little later and with 7 sec subs. But it was still daylight

my first 2 mins sub looks good gonna look at stats

100 ish x 1 min which is pretty good 

i think the flag im shooting through/past is making my guiding a bit [removed word]. once i lose m16 for the night in about 30 mins ill try ngc6888 crescent nebula can compare it my broadband version...

....which is what a sensible person might say. I'm tempted to go squid hunting.

Edited Wednesday at 21:28 by TiffsAndAstro

[Stuart1971]

On 26/08/2024 at 20:07, TiffsAndAstro said:

Sadly siril only has a split Ha/Oiii script. I'll look see if anyone wrote one I could use or maybe edit the values to work on different frequencies.

Lots of options on pallettes.

I meant do I need filter specific darks and biases? Do you use different dark and bias  library sets for each filter?

Thanks for the help

No, as they are darks, so they don’t care what the filter is as they can’t see it….👍🏻

[TiffsAndAstro]

17 minutes ago, Stuart1971 said:

No, as they are darks, so they don’t care what the filter is as they can’t see it….👍🏻

was just double checking ty

[TiffsAndAstro]

for 2 mins, looks ok. guiding is a bit iffy hoping its how low it is in the sky. im zoomed in a bit in nina. also no clipped pixels dark or bright. which i think is ideal?

Edited Wednesday at 22:08 by TiffsAndAstro

[WolfieGlos]

Looks good to me 👍

Yes, guiding will be worse the closer you get to the horizon. My guiding was 2” and higher if I recall on M20 a few months ago. Subs were still fine though.  

Im currently aimed up in Cepheus so near the zenith - guiding has been 0.5” ALL night. I’ve never had that before! Just a shame I’ve just lost 20 minutes of subs since the scope dewed up 🤦‍♂️ Caught me totally by surprise, so watch out. 

Edited Wednesday at 23:21 by WolfieGlos

[TiffsAndAstro]

6 minutes ago, WolfieGlos said:

Looks good to me 👍

Yes, guiding will be worse the closer you get to the horizon. My guiding was 2” and higher if I recall on M20 a few months ago. Subs were still fine though.  

Im currently aimed up in Cepheus so near the zenith - guiding has been 0.5” ALL night. I’ve never had that before! Just a shame I’ve just lost 20 minutes of subs since the scope dewed up 🤦‍♂️ Caught me totally by surprise, so watch out. 

I took a 10 minutes test on squid and saw no squid. So I went to the safer plan. 

[WolfieGlos]

14 minutes ago, TiffsAndAstro said:

I took a 10 minutes test on squid and saw no squid. So I went to the safer plan. 

Good call. I might give it a go with my SY135 one day, but that’s only because it’s f2.

[TiffsAndAstro]

Er clouds so doing flats

Is 9 seconds unusually long?

[TiffsAndAstro]

1 hour ago, WolfieGlos said:

Good call. I might give it a go with my SY135 one day, but that’s only because it’s f2.

It's a great area for stuff.

[Stuart1971]

6 hours ago, TiffsAndAstro said:

Er clouds so doing flats

Is 9 seconds unusually long?

I do all my flats at 4 seconds, 9 seconds seems a bit long, but if they are good then try them..👍🏻