From the Iris to LDN 1152

[gorann]

Now I can soon read a paper outside at midnight here, so I am processing and mixing old data. This is a mix of RASA8 with ASI2600MC from 2020 and 5" refractor data from 2016 (ES 127ED and Canon 60Da). Maybe inspired by the bright nights up here right now I made it quite bright. The full field is from the RASA while the refractor data was added to the area around the Iris nebula. Totally 13 hours processed in PI and PS.

Cheers. Göran

Edited May 21, 2022 by gorann

[vineyard]

That would be a great Halloween shot.

[simmo39]

Another stunning shot!

[gorann]

9 hours ago, vineyard said:

That would be a great Halloween shot.

 

15 minutes ago, simmo39 said:

Another stunning shot!

Thank you both!

CS Göran 

[Rodd]

Wow.  Makes me realize I am wasting my time

[Elp]

Rasa exp time = how much time for us mere mortals?

[gorann]

1 hour ago, Rodd said:

Wow.  Makes me realize I am wasting my time

Thanks Rodd, but from I have seen coming from you, you are clearly not waisting your time!!!

[gorann]

1 hour ago, Elp said:

Rasa exp time = how much time for us mere mortals?

He he, why not get a RASA😉. Not very expensive (at least compared to the Tak alternatives) and the relatively low weight and short focal length means that it can sit on a rather affordable mount. Biggest challenge is the fiddeling with sensor distance

[tomato]

Great image, love all that tortured gas and dust!
 

+1 for the RASA8, despite being an F2 reflector, it has been on and off my mount half a dozen times but has required no collimation, it holds it’s focus very well also.  For going deep in the minimum of exposure time, I don’t think there is a better scope out there for the money.

[Rodd]

3 hours ago, gorann said:

Thanks Rodd, but from I have seen coming from you, you are clearly not waisting your time!!!

Take a look at the IOTD of ngc 6888 from yesterday. He has 12hours of so total and I’ll soon have 10 just in Ha and the image will never be as good.  Not with 100 hours.  

[gorann]

5 hours ago, Rodd said:

Take a look at the IOTD of ngc 6888 from yesterday. He has 12hours of so total and I’ll soon have 10 just in Ha and the image will never be as good.  Not with 100 hours.  

Yes I was also impressed by that one as it is exceptional and probably aquired under exceptionally good conditions.

[wimvb]

5 hours ago, Rodd said:

Take a look at the IOTD of ngc 6888 from yesterday. He has 12hours of so total and I’ll soon have 10 just in Ha and the image will never be as good.  Not with 100 hours.  

Rodd, that image is from an amateur hosting facility, which is probably located at a dark site. And even though xlong complains about light pollution, that may not even come close to what you have. Total integration time more than doubles for every magnitude you lose in darkness. If your sky has a brightness of, say, magnitude 17, and xlong has 19, you will need 6 times as much integration time. I agree with Göran; from what I've seen from you lately, you're definitely not waisting your time. So, please keep those pretty pictures coming. Btw, Göran has 21.5 Mag sky darkness. That, in combination with a double f/2 RASA, and sensitive ZWO cameras, is almost cheating 😉😉

Very nice rework btw, @gorann.

[gorann]

9 hours ago, tomato said:

Great image, love all that tortured gas and dust!
 

+1 for the RASA8, despite being an F2 reflector, it has been on and off my mount half a dozen times but has required no collimation, it holds it’s focus very well also.  For going deep in the minimum of exposure time, I don’t think there is a better scope out there for the money.

Yes, maybe even +2👍 Its ability to hold focus is surprising. In my experience it holds focus as long as the temperature does not fall more than 3-4 °C. Many slower telescopes appear to be more temperature sensitive.

Edited May 23, 2022 by gorann

[Elp]

11 hours ago, gorann said:

He he, why not get a RASA😉. Not very expensive (at least compared to the Tak alternatives) and the relatively low weight and short focal length means that it can sit on a rather affordable mount. Biggest challenge is the fiddeling with sensor distance

Thought about it, but in my light polluted area it'll probably just amplify collection of that signal also. The added requirement of faster filters and possibly another camera puts me off. Hyperstar route is another option but the same added requirements apply. Atm I'll just keep adding to the 10 odd hours I've acquired on the Iris for now.

[gorann]

5 hours ago, Elp said:

Thought about it, but in my light polluted area it'll probably just amplify collection of that signal also. The added requirement of faster filters and possibly another camera puts me off. Hyperstar route is another option but the same added requirements apply. Atm I'll just keep adding to the 10 odd hours I've acquired on the Iris for now.

I am fortunate enought to have my obsy at a dark site (SQM ca 21.5), but I get regularly light polluted by the moon 😄 and then I use an IDAS NBZ dual band (Ha Oiii) filter with the RASA8. Not very expensive. I assume it would work well with other light pollution too. Here is an example with 60% moon on 11 April. Even if you do not go for a RASA8, an IDAS NBZ may be worth trying.

Cheers, Göran

Edited May 23, 2022 by gorann

[Elp]

Excellent images overall.

I was thinking more about SHO filters, I have the whole set already, lrgb and all the main Optolongs. With a RASA/hyperstar I'd probably have to buy them all again barring the latter.

Always wondered about the NBZ, there's also a UHC which isn't so aggressive, I'm assuming the Optolong L-Enhance/Extreme will be similar to the NBZ but haven't got around to trying them yet (can only try them with a DSLR atm).

Shooting the Iris will always be difficult where I am in bortle 7, with 6.5 hours of luminance the detail around the main star and first "barrier of dust" has only started to spill onto the next barrier of dust. The remaining time is RGB but I've decided to stick with getting more luminence for now or wait until I get to go to a dark site. The clear nights have been terrible this year, only get to shoot once or twice a month.

 

[ollypenrice]

Great image. I never get dust to look like that, with such a brightness range. Although it's pushed very hard it's also impressively clean. I must admit that I'd like to peep over your shoulder when you process your dusty stuff...

😁lly

[tomato]

This dark shark image is 3 hrs integration with a RASA8/IMX571OSC from a Bortle 5/6 site and I would venture that you can still get the benefit of the fast optics and don’t need pristine skies to get reasonable results.

 

[gorann]

2 hours ago, ollypenrice said:

Great image. I never get dust to look like that, with such a brightness range. Although it's pushed very hard it's also impressively clean. I must admit that I'd like to peep over your shoulder when you process your dusty stuff...

😁lly

Thanks a lot Olly! For some reason it comes natural with the RASA data - never happened with my refractors. But then I also started using starless processing of the nebulosity which really helps to lift the nebulosity.

Göran

[gorann]

2 hours ago, tomato said:

This dark shark image is 3 hrs integration with a RASA8/IMX571OSC from a Bortle 5/6 site and I would venture that you can still get the benefit of the fast optics and don’t need pristine skies to get reasonable results.

 

Impressive Steve, which empasises the natural brightness that somehow comes out of the RASA.

Cheers, Göran

[Fegato]

10 hours ago, gorann said:

Thanks a lot Olly! For some reason it comes natural with the RASA data - never happened with my refractors. But then I also started using starless processing of the nebulosity which really helps to lift the nebulosity.

Göran

It's a wonderful image. I know that a lot of integration time is a pre-requisite, and I too often do starless processing of an image like this, but would it be rude of me to ask what technique you used to get such a clear separation of the dust from the background?  Thanks!

[gorann]

1 hour ago, Fegato said:

It's a wonderful image. I know that a lot of integration time is a pre-requisite, and I too often do starless processing of an image like this, but would it be rude of me to ask what technique you used to get such a clear separation of the dust from the background?  Thanks!

Thanks a lot Fegato!

Nothing special. I always stretch in several small iterations (7-10 usually) using an S-shaped curve. Then I made the starless version and stretched once more shaping the curve to increase dust and suppress the sky. Finally I Hi-Pass filtered the starless image to separate out the dust a bit more. Then I added back the stars as a layer and controlled their size with a curve. All in PS.

[Fegato]

32 minutes ago, gorann said:

Thanks a lot Fegato!

Nothing special. I always stretch in several small iterations (7-10 usually) using an S-shaped curve. Then I made the starless version and stretched once more shaping the curve to increase dust and suppress the sky. Finally I Hi-Pass filtered the starless image to separate out the dust a bit more. Then I added back the stars as a layer and controlled their size with a curve. All in PS.

Thanks. I need to practice my curves I think! I use PI so slightly different, but I guess doing the same thing. I probably tend to get a bit impatient too once I get into the post processing!....

[gorann]

4 hours ago, Fegato said:

Thanks. I need to practice my curves I think! I use PI so slightly different, but I guess doing the same thing. I probably tend to get a bit impatient too once I get into the post processing!....

Patience is the key. I rarely spend less than a day on processing an image, with many small steps.

[wimvb]

12 hours ago, Fegato said:

Thanks. I need to practice my curves I think! I use PI so slightly different, but I guess doing the same thing. I probably tend to get a bit impatient too once I get into the post processing!....

When it comes to stretching, both programs are not that much different. PIs Histogram Transformation is Levels in PS. Curves is the same in both. Never ever use the screen transfer function in PI as part of your permanent stretch. Like Göran, I stretch in small iterations. I start with Histogram Transformation, where I place the black point just shy of clipping even one pixel. I set the mid point to 0.25. I apply this stretch as many times as needed, usually to get the background to 0.1. Then I move to Curves, where I put a marker under the histogram peak (now at 0.1) and pull it down to 0.75 - 0.8 (edit: 0.075 - 0.08) A second marker at 0.25 - 0.35 and pull that up. This creates the basic S-curve, but will over stretch the bright areas. A third marker at 0.8 - 0.85 ensures that the bright parts won't be over stretched, and a fourth marker between nrs 2 and 3 in order to create a smooth S curve, where the upper part is almost linear. A curve like this stretches the dark areas more than the bright areas while keeping the noise down and the stars under control. On a starless image you can be more aggressive, of course.

Edited May 24, 2022 by wimvb