Newbie: What am I doing wrong? Everything?

[drivera]

Hey there,

I'm a complete newbie to this sport ;-) and I'm struggling to get any type of quality images from my imaging. Now I understand I am limited with my equipment but I feel I'm doing something wrong.

My setup:

- Sony A7iii (not modded) - DSLR I own and have, so wont be changing this unless I get a pay bump!
- Redcat 51
- Sky Guider Pro
- ZWO ASI120MM Mini guide camera
- Raspberry Pi 4 - hooked with guide camera to mount ST4, USB to Pi, and Camera shooting through ekos.
- Filter: (is this my issue?): Explore Scientific O-III Nebula Filter 2" https://www.rothervalleyoptics.co.uk/explore-scientific-filters/explore-scientific-o-iii-nebula-filter-2.html

Location: Kent, UK - Bortle 5.

I know at this stage, no astro darkness and limited nighttime anyway.

So my first attempts have been North America Nebula and then the Veil Nebula. 
I've shot about 2 hours of NA and about 1 and half hours of the Veil Nebula.  
- ISO: 1600
- Exposure: 300secs
- Whitebalance - Auto
- Darks: 15
- Flats 10
- Biases 50
 

Firstly, I get the green layer, which is from the filter I believe but it is so strong across my images. I've been trying to learn PixInsght and have been following the LightVortexAs processing. 
My images come out like the attached after the processing. I assumed the green/aqua tint is the filter and then separate the channels and use PixelMath to combine and bring more colour but the overall image changes colour not the nebula. I've also I tried to do PhotometricCalibration and it removes the green a bit but the quality just isn't there. I can't pull any depth to the images and the colours are rubbish. I'm at a loss, I assume being only Oiii I'm limiting my colours and with a DSLR I'll have higher noise. But... I'm seeing other people who fantastic shots from DSLRs with even less exposure time. 

Is this due to having a too high ISO with my exposure time.  Trying to pull any data, especially the Veil nebula it's so weak. The NA seems to have more data but I still can't extract anything?
The attached are screenshots from PixInsight, so you won't see the lack of quality beyond the shot but I'm wonder if someone can help me understand where I'm going wrong - what I'm doing?

 

Thanks so much
Steve

[vlaiv]

Hi and welcome to SGL.

Yes, filter is the problem.

That filter is narrowband filter that passes only single wavelength of light. It is good for visual use or when you image with mono camera and other narrowband filters to produce false color (say HST palette) narrow band image.

You have chosen two targets that emit in OIII - so that is good and you have some signal, however, since this is basically a single wavelength of light - don't expect any color in it - it is monochromatic image by nature - even if you capture it with OSC sensor.

Filter is good to combat light pollution - if you are happy with monochromatic images of only OIII signal. However, if you want to go that route - maybe Ha filter would be better option as H alpha signal is generally much stronger and more targets shine in Ha.

Alternatively - if you want to do regular color photography - maybe try without filter first. At Bortle 5 sky - LP filter can sometimes hurt more then help. If you know the type of light pollution you have - mostly yellow street lighting meaning High pressure sodium lights - then yes, get LPS filter, but if mostly you have broad band - led type light pollution - just shoot unfiltered or get Astronomik L3 filter if you notice that your scope is giving you a bit of bloat in blue part of spectrum (slight chromatic aberration).

 

[drivera]

Thanks so much for the fast reply and the welcome!

Thanks for clarifying that - it's definitely a learning curve here but glad I was on the right track.

I did buy a Svbony CLS filter previously but never used it and they said the below - but I heard Svbony aren't the best.

"The CLS filter is designed to enhance the transmission of main nebula emission lines at OIII(496nm and 500nm), H-beta (486nm), NII(654nm and 658nm), H-alpha(656nm) as well as SII(672nm) ; Suitable for CCD cameras unmodified DSLR and any 2 inch eyepiece". Would that be more suitable?

I was reading about people on the 'l-Enhance / extreme filters' so I didn't know if thats the path I should have taken or as you said first go down with no filter and then work from there?

 

Thanks again,

Steve

[vlaiv]

2 minutes ago, drivera said:

I did buy a Svbony CLS filter previously but never used it and they said the below - but I heard Svbony aren't the best.

CLS is rather crude type of LPS filter.

It is not as aggressive as UHC type filter but does throw off color balance quite a bit and looses important parts of spectrum.

Whether it is going to work depends on what type of target you'll be imaging and what is composition of your local light pollution.

For emission type targets - it will be better than OIII type filter. It will give you good color of targets themselves, but star colors will suffer.

You can't get proper star color with CLS type filter. You can circumvent this by taking two sets of subs - one filtered and one unfiltered - and then using star color from unfiltered set of subs and everything else from filtered set of subs.

If you are going to image anything else - like galaxies or clusters or reflection nebulae - it is likely that using CLS filter will hurt more than it will help - unless you have very specific type of light pollution.

I would recommend that you try both - not using filter and using that CLS filter - but use CLS filter only on emission type nebulae and Ha regions. This time of the year (and a bit later - beginning of autumn) a lot of interesting Ha regions will be available for imaging. You should take advantage of that and just experiment.

10 minutes ago, drivera said:

I was reading about people on the 'l-Enhance / extreme filters' so I didn't know if thats the path I should have taken or as you said first go down with no filter and then work from there?

Extreme UHC type filters and duo / tri / quad filters work ok - again for specific types of targets. However, you are in not that big LP to absolutely must use some sort of filtering for imaging.

[newbie alert]

Hi Steve, abit off topic but where in Kent are you?

[drivera]

I'm in the Cudham/Knockholt area 🙂 How about yourself?

[drivera]

52 minutes ago, vlaiv said:

CLS is rather crude type of LPS filter.

It is not as aggressive as UHC type filter but does throw off color balance quite a bit and looses important parts of spectrum.

Whether it is going to work depends on what type of target you'll be imaging and what is composition of your local light pollution.

For emission type targets - it will be better than OIII type filter. It will give you good color of targets themselves, but star colors will suffer.

You can't get proper star color with CLS type filter. You can circumvent this by taking two sets of subs - one filtered and one unfiltered - and then using star color from unfiltered set of subs and everything else from filtered set of subs.

If you are going to image anything else - like galaxies or clusters or reflection nebulae - it is likely that using CLS filter will hurt more than it will help - unless you have very specific type of light pollution.

I would recommend that you try both - not using filter and using that CLS filter - but use CLS filter only on emission type nebulae and Ha regions. This time of the year (and a bit later - beginning of autumn) a lot of interesting Ha regions will be available for imaging. You should take advantage of that and just experiment.

Extreme UHC type filters and duo / tri / quad filters work ok - again for specific types of targets. However, you are in not that big LP to absolutely must use some sort of filtering for imaging.

Thanks so much - really interesting insight and info for what I'm learning!! Thanks again!

[newbie alert]

8 hours ago, drivera said:

I'm in the Cudham/Knockholt area 🙂 How about yourself?

I'm in Ashford...

I'm going to pm you some info

[david_taurus83]

Try without any filter to start with. 

[drivera]

13 hours ago, newbie alert said:

I'm in Ashford...

I'm going to pm you some info

Amazing thank you!

[drivera]

12 hours ago, david_taurus83 said:

Try without any filter to start with. 

Definitely going down that path now. I tried to run before I could walk it seems! Even though I did ask a reseller if that filter was right - but maybe I should have researched and questioned 🤷‍♂️