Processing help - is my data bad or is it me?

[TerraC]

Would anyone mind seeing if they can pull anything from this data please?  I'd had a go but i'm hopeless with processing and I'd like to know if my data is any good or it's just me.  I'm expecting both are bad.  Shot with a 72ED and a Canon 550d.   4.5hrs of 60sec lights.  30min of darks.  

Bortle 6 location so a bit of light pollution here.  I suspect issues with DSLR.  Not sure if it needs a sensor clear but thinking of having it modified soon anyway.  Histogram 1/3rd from left. ISO 800. 

I'm still learning processing and have been playing with both photoshop and startools.  I can get something out of it but not anywhere near what I was expecting for 4.5hrs.  In fact I seem to get similar results from 30mins of data.  I'll keep plodding away and learning techniques but if the data is bad from the outset i'd need to start over.

thank you

Ray

 

 

Autosave2.tif

[Gary Clayton]

Hi Ray

I had a quick play with your data, the main issue is the very strong light pollution causing a strong gradient across the image, did you use a light pollution filter?.

[TerraC]

Thank you - looks a lot finer detail than i've managed to pull out so far. 

No I think LP filter is something I need to invest in whilst shooting from this location.   Possibly a clip in for the Canon. 

I have an old 1 1/4 CLS filter from an old system.  When I got the 72ED it's 2" straight through with a field flattener so would have trouble linking together. 

I appreciate i'm using some budget gear so definitely not expecting miracles  Happy to see anything and learn what i'm doing wrong. 

[geeklee]

3 hours ago, TerraC said:

In fact I seem to get similar results from 30mins of data.

It's always hard to tell because everyone's localised light pollution is different but it does seem like 4.5hrs should give you a touch more.

The focus looks a little soft, or could there have been high cloud and a lot of moisture during this night?  Did you have a dew heater on?

Was the data calibrated with Flats?

The background was tricky to remove and I never managed fully as I was trying to be as light touch as possible.  I gave it a gentle stretch, reduced the stars a bit and tried to get a some more colour (didn't really manage the last one)

I'm not sure if you were getting similar to the above yourself?

Don't be disheartened, processing is a huge part of AP and not knowing if you're getting the data captured to your own satisfaction adds another variable.

Edited November 15, 2022 by geeklee

[happy-kat]

Could you do a stack with lights and if you have them flats too please. Darks with the dslr might be adding more noise.

[vlaiv]

I'm guessing that there are several issues with this image.

1. Poor transparency / high altitude clouds or perhaps even foggy conditions at the imaging site - there is certain "softness" to the image that indicates this

2. Lack of field flattener and some tilt issues. What can be seen as poor focus is actually due to field curvature and tilt in my opinion

3. Lack of flat fields

[geeklee]

4 minutes ago, vlaiv said:

What can be seen as poor focus is actually due to field curvature and tilt in my opinion

Thanks @vlaiv It was the softness that was throwing me on this - hence mentioning focus. 

When clearing the background many different ways, everything was left with ghosting around it like cloud/fog/mist etc.  I wasn't sure I had got the background extracted correctly but if the sky was like this then perhaps it was.

[TerraC]

@geeklee  It was a damp night yes. I was using a SVBony dew heater on medium setting.  (boy does that thing eat battery power - but that's another story.)     Thank you that's way better than i've been doing.  What are you using to process? Pixinsight?  

 

@happy-kat No i've tried to shoot flats a couple of times but I dont think I am getting them right.  They seem to make the stack result worse.  I'll try attach a stack with only lights.  i'm using Deep Sky Stacker.  

[TerraC]

@vlaiv - Thank you.  I need to perfect some flat frames I think.  I tried the Tshirt and light trick. T-shirt and sun.  The lights I shot seemed to make things worse rather than better. 

Currently using a Stellamira Flattener on the 72ED.   

 

Think i'll have to shoot new flats and work with some new data on a clearer night and see what I get. 

 

[geeklee]

12 minutes ago, TerraC said:

(boy does that thing eat battery power - but that's another story.) 

As an aside...  I once had a retailer branded dew strap (not large, probably similar to covering a 72ED) and the first time I tried it was a short clear spell.  When I took my gear in the scope was almost hot to touch!  It was pulling a silly amount of power, even adjusted (for a smaller dew strap).  It went straight in the bin.  The smaller ones I have now (for slightly smaller scopes than the 72ED) are ~0.3-0.5A @ 12v, so ~3.6-6w.  These are W&W Astro/Dew Control and AstroZap.  The former has power specs on their site for each size 👍

A long way of saying... is yours also getting too hot? 😅

12 minutes ago, TerraC said:

What are you using to process? Pixinsight?

Yeah 👍 

Edited November 15, 2022 by geeklee

[TerraC]

I was wondering if it was getting too hot but to the touch it was just gently warm.  It drained a 10,000mah power pack in around 2 hours though.  My Canon 550d will run off this pack for 2 - 3 nights without a charge.   I read someone said to remove the controller for the dew heater but it runs on full power then and they say it gets a bit warm! 

Attached a stack of just lights.  straight from DSS. 

Autosave.tif

[knobby]

My effort on the original file in post 1

Siril software.

Slight crop - background extraction (twice 🙂 ) - Archsinh curves - photometric colour calibration - saturation boost.

Quite a lot of signal in there, possible tilt and incorrect flattener spacing maybe and focus looks a tad off but  nice image !

 

[geeklee]

23 minutes ago, TerraC said:

Attached a stack of just lights.  straight from DSS. 

Seems much easier to show the great detail you've captured in the central lanes.  Also a little subtle detail in M110 👍

This isn't really processed.  Just a very rough background extraction and a light stretch (with the new file)

Edited November 15, 2022 by geeklee

[ONIKKINEN]

1 hour ago, TerraC said:

I was wondering if it was getting too hot but to the touch it was just gently warm.  It drained a 10,000mah power pack in around 2 hours though.  My Canon 550d will run off this pack for 2 - 3 nights without a charge.   I read someone said to remove the controller for the dew heater but it runs on full power then and they say it gets a bit warm! 

Attached a stack of just lights.  straight from DSS. 

Autosave.tif 169.21 MB · 3 downloads

Ran this through my (current) processing workflow. The data is definitely workable, but requires some heavy touchups on the background due to the purple bias noise in the 550D (red and blue have bad QE, so all the noise is there).

Processed in ASTAP, Siril and photoshop. Photoshop tools used: GradientXterminator, StarXterminator, TopazAI denoise.

First inspected the image in Siril for star sizes which led me to bin the image x3 in ASTAP. Have to save as .fit first as ASTAP doesnt want to work with the DSS .TIFF.

In Siril: Background extraction for an initial gradient removal, this reveals the spotty background but its the best that siril could do and at this point its maybe ok but ill come back to it later. Photometric colour calibration with used star magnitudes set to 16, just based on how much signal i think there is. After this, "green noise removal" which is just SCNR green. Asinh transformation at 1000 power and some blackpoint adjustment until the background is almost clipped but nothing is at 0.

In photoshop: Create a starless layer and a stars only layer with StarXterminator. Leave the stars as is to add later on back to the image, export the starless layer to a further stretch in Siril (just histogram transformation). Send that back to photoshop and use that as the galaxylayer from here on out. First i selected the background with the color range tool and desaturated it by -90, this removes a large chunk of the RGB noise of the background, then secondly GradientXterminator with the aggressiveness set to high to nuke the background further, but still some spots and streaks remain (looks like might be walking noise from polar alignment, it is almost north-south aligned but not quite, dither to avoid this!). The spots that remain i removed with the lasso tool and "fill" function with content aware filling. Some healing brush around the edges where content aware fill is confused and doesnt quite know how to fill. Also applied some denoise on just the background at this point. Then in Camera Raw i adjusted the colours a little bit (they were too magenta) and applied some texture and clarity to bring the dust lanes and galaxy detail forward. TopazAI denoise with the low light AI set to 1 denoise and 1 sharpness to the galaxy layer and save, then smart sharpen for the galaxy layer a little bit. For the stars-only layer i applied a kinked curve to stretch the dimmer stars but leave the brighter ones unaffected, this makes the image look a bit more "organic" when the stars are still there but not at the forefront. Some saturation for the star layer to bring out the different stellar temperatures.

Below an image with a heavy diagnostic stretch that shows the issues in the image better:

'

The bottom thing looks a bit like some of your subs where off target a little bit, and with some camera rotation angle difference too. Could be something that flats take care of too, hard to say. The spots and lines are what gave the most trouble in the image for sure, but running GradientXterminator and filling the spots iteratively ultimately fixed that issue.

Edited November 15, 2022 by ONIKKINEN

[TerraC]

Wow fantastic result. Really appreciate your efforts and description of workflow. 

I think i'll start again from scratch and look into getting some decent flats.  Then have a play with the tools you have used. 

 

[ONIKKINEN]

2 minutes ago, TerraC said:

Wow fantastic result. Really appreciate your efforts and description of workflow. 

I think i'll start again from scratch and look into getting some decent flats.  Then have a play with the tools you have used. 

 

Processing is a bit of a voodoo art and you will improve with every image you process, just keep at it.

The tool that makes the selective processing possible here is StarXterminator. That one costs some money, but i think its worth it. Starnet++V2 also exists, which is free and i think almost as good as StarX: https://www.starnetastro.com/download/

Definitely give starless processing a try, it will improve just about any image.

[vlaiv]

2 hours ago, TerraC said:

Currently using a Stellamira Flattener on the 72ED.   

Ok. That is good - but I would check few things.

First is attachment. As far as I can tell - you can unscrew 2" nose piece on that flattener to reveal M54 thread according to Flo:

From what I quickly gathered around the net - 72ED also has that thread on focuser (once you remove clamping ring).

Maybe it's not the same thread and you'll need adapter - but it might be the same, in which case you can just directly screw it in.

Screw in connection is much much better than clamping one as clamping one can easily introduce tilt.

I would also experiment with 55mm back focus - back focus depends on field curvature of the scope which in turn depends on focal length of the scope. 55mm should be seen as a guide line - not as a precise thing, unless reducer/flattener is optically matched to the scope.

Here are stars in corners of your first uploaded image:

defined core + ring is sign of either very poor chromatic correction (like when you don't use UV/IR cut filter) or sign of defocus.

other corner shows similar thing - but astigmatism as well.

Third one is not as bad:

still a bit defocus but not as bad as other two - which suggests there is tilt

On the other hand center of the field shows nicer stars compared to corners:

All of that is indicative of tilt and field curvature (different focus position for center and edges of the frame) - which flattener is supposed to correct. If it's not correcting, but is present - it usually means spacing issue.

For tilt - check if you can switch to threaded connection

For curvature - try playing around with spacing to see if you can get better results.

 

[TerraC]

Looks like i need some kind of adapter.  The connector on the 72ed is male ended and plain inside. The stellamira slides inside and holds in with 2 thumbscrews. The stellamira comes apart but they are female threads that wont link to the 72ed. 

 

[vlaiv]

33 minutes ago, TerraC said:

Looks like i need some kind of adapter.  The connector on the 72ed is male ended and plain inside. The stellamira slides inside and holds in with 2 thumbscrews. The stellamira comes apart but they are female threads that wont link to the 72ed. 

This seems to be the answer:

https://www.firstlightoptics.com/adapters/astro-essentials-m54-adapter-for-sky-watcher-newtonians-and-72ed-refractor-m54.html

but probably best check with FLO before ordering if it will truly work for our use case.

[AstroNebulee]

56 minutes ago, TerraC said:

Looks like i need some kind of adapter.  The connector on the 72ed is male ended and plain inside. The stellamira slides inside and holds in with 2 thumbscrews. The stellamira comes apart but they are female threads that wont link to the 72ed. 

 

On my 72ed I've used a ovl FF (which I believe is the same as a Stella mira one) removed the nose piece as you have and placed a m48 female to male RVO rotator, then a male m48 to M54 male adapter into the focus tube.

https://www.firstlightoptics.com/adapters/astro-essentials-m48-adapter-for-sky-watcher-newtonians-and-72ed-refractor-m54.html

You can just not have a rotator if you want. The one from RVO is much better quality than the skywatcher 72ed rotator as more solid and doesn't slop about when the thumbscrews undone to rotate. Its more pricey I think but so much better quality. 

https://www.rothervalleyoptics.co.uk/rvo-m48-caa-360-rotator.html

I think the measurements are correct. 

Lee 

Edited November 15, 2022 by AstroNebulee

[TerraC]

@AstroNebulee Thank you that's great. Ive ordered the adapter for now and will get a rotator a little later. 

 

[AstroNebulee]

1 hour ago, TerraC said:

@AstroNebulee Thank you that's great. Ive ordered the adapter for now and will get a rotator a little later. 

 

No problems, I hope my measurements were correct. When you do get the rotator definitely get the RVO one much better. 

Lee

[WolfieGlos]

On 18/11/2022 at 16:15, AstroNebulee said:

No problems, I hope my measurements were correct. When you do get the rotator definitely get the RVO one much better. 

Lee

I’m glad I found this, I was waiting for the Skywatcher rotator to come back into stock, but if this RVO one is better then I will get it on order, especially if it works with the M54 to 48 adapter to the stellamira flattener. @AstroNebulee Does it accept 2” filters like the skywatcher one? 

@TerraC
The M54 to M48 screwed adapter made a big difference to my tilt levels. If you have Astap or Siril (both are free) you can check your tilt values. You can see the topic we have been discussing it on here: 

https://stargazerslounge.com/topic/394618-need-some-advice-on-collimating-a-72ed/

Although my tilt still exists, I’ve now added these tilt adjusters: https://www.firstlightoptics.com/adapters/astdym_m42_tilt_adjuster.html

Last night was my first real test with them , 4 hours on the Veil and it’s averaging 5% tilt, some frames show none. Andromeda is my next target when I’ve finished so I might try playing with backfocus again. Hope this helps.

[AstroNebulee]

20 hours ago, WolfieGlos said:

I’m glad I found this, I was waiting for the Skywatcher rotator to come back into stock, but if this RVO one is better then I will get it on order, especially if it works with the M54 to 48 adapter to the stellamira flattener. @AstroNebulee Does it accept 2” filters like the skywatcher one? 

@TerraC
The M54 to M48 screwed adapter made a big difference to my tilt levels. If you have Astap or Siril (both are free) you can check your tilt values. You can see the topic we have been discussing it on here: 

https://stargazerslounge.com/topic/394618-need-some-advice-on-collimating-a-72ed/

Although my tilt still exists, I’ve now added these tilt adjusters: https://www.firstlightoptics.com/adapters/astdym_m42_tilt_adjuster.html

Last night was my first real test with them , 4 hours on the Veil and it’s averaging 5% tilt, some frames show none. Andromeda is my next target when I’ve finished so I might try playing with backfocus again. Hope this helps.

Hi Wolfie 

I don't think you can put 2inch filters in the RVO rotator, I use a filter drawer so wasn't a problem when using my astronomik L3 filter. If you can install your filter elsewhere I'd still definitely get the RVO rotator much more sturdy and no wobble when the thumbscrews are undone. On my RVO one I just needed a tiny tiny drop of washing up liquid to help lubricate it and it's brilliant. 

Lee