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Old 13-10-2019, 08:52 PM
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Zubenel (Wes)
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Help with the Eagle

With a 50% moon last week-end I gave the Eagle Nebula or more specifically the Pillars of Creation 320 Lights and 9 Darks x4 sec with UHC Astromik Filter stacked in Sequator ( DSS didnt complete twice=Fail) has given the result of a nasty cross grid shaped pattern. I haven't been able to remove this aberration using Gimp or PS Cs3 (which I'm new too). I would appreciate some advice. In hopes of such here is a link to the raw file ( 93MB)! https://naa5r8c6.filegear.me:9443/l/r/n/s/lbimevai
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Old 13-10-2019, 09:02 PM
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9 darks are nowhere near enough you need at leat 50 for the amount of lights you used. Also your raw file is already processed so not much scope to play with it.

Do you have he originals somwhere to download? Also the darks
cheers
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Old 13-10-2019, 09:24 PM
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This looks like the work of your LP filter. It's clipping some of the good light as it tries to filter the unwanted light within the spectrum. As Nik has suggested if you can post a raw sub we may be able to identify the cause.
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Old 13-10-2019, 10:08 PM
RyanJones
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Hi Wes,

Firstly Iím not going to pretend that I ď know ď what is causing that pattern so please take my suggestion with a grain of salt.

I did a little reading about your camera ( assuming itís the Olympus you list in your signature ). I think the pattern has been caused at a sensor level. I have two theories. 1 is that if youíre using a really high ISO, you maybe amplifying a pattern in the sensor construction that normally wouldnít be noticed ? My second guess would be that I noticed your camera has mechanical image stabilization for low light ? Is it switched off ? Can it be ? This pattern could be caused by the image shift of the stabilization? I have picked my own holes in my own arguements but I hope maybe this might help ?
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Old 13-10-2019, 10:54 PM
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Thanks guys for such an avalanche of assistance.
Nicolas, thx for the advice on the darks, Iíll make sure I take more next time. Iíll upload a new link tomorrow night with the unadultered raw file ( not stretched)
Thx also LIS👍🏻😊
Ryan, Iíll check the image stabilisation setting . I think it may of been turned on so nice pick up .The iso was 2000. Not much above the optimal 1600. Thx
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Old 14-10-2019, 07:08 PM
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Here is a new link to the a TIF image which is the outputed file from sequator. I note it's not in raw format Does this mean that I'm missing something fundamental regarding the base file requirements at the starting point of post editing ( I hope I'm making sense here ) https://naa5r8c6.filegear.me:9443/l/r/n/s/qr3blljr
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Old 14-10-2019, 07:14 PM
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rustigsmed (Russell)
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have you turned the star detection threshold down in DSS? what was the fail error?

Have you tried stacking without the darks?
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Old 14-10-2019, 07:18 PM
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rustigsmed (Russell)
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it looks like fixed noise pattern to me. You should look at dithering your subs when capturing to reduce the effects.

http://dslr-astrophotography.com/dit...rophotography/

edit im not sure there is much you can do with the image. If it were me - i would take LOT of darks and try to apply them in DSS.

Last edited by rustigsmed; 14-10-2019 at 07:30 PM.
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Old 15-10-2019, 11:23 AM
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Try doing a few duplicates give each just one colour then merge them one by one in photo shop using the rubber tool and I bet you end up with a pretty flash image.
Alex
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Old 15-10-2019, 12:47 PM
Startrek (Martin)
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I started using a CLS filter with my Canon 600D when in Sydney under Bortle 8 skies but left the subs with a blueish tinge and couldnít totally eliminate it post processing
So I eventually ditched the filter. I use DSS to stack and Startools to remove all types of noise , does a superb job and wonít clip your data
If you use DSS to stack , stack at least 20 or 30 at same exposure length and ISO as your subs and preferably straight after your subs
In DSS under the darks tab ďdo not checkĒ Dark Optimization as it can play havoc with your darks
Also previously mentioned , dithering is a must using DSLRís especially coming into the warmer months
Hope you solve your issues
Good luck
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Old 15-10-2019, 01:14 PM
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Just to chuck an ocelot in with the chickens... the cross hatching I dont think is any of the suggested items. Think in terms of physics. Photons comer through the optical train and exist the OTA/lens and touch nothing until they hit the sensor, then what? they are recorded but the sensor is a flat shiny surface so what happens? the photons reflect back and what do they hit? the last element in the optical train which is smooth and shiny and so reflect back. Yes energy is lost during all this but the photons dont magically get saved into the memory card and cease to exist their energy level is recorded though. some energu is lost through heat when it touched the sensor, some is scattered but the surface of the sensor is a grid of different substances/colours so reflecting the photon back with much less strength then it hits the last optical surface in the optical train and much of the photon travels outwards losing energy but some small amount is reflect back again. think of standing between two parallel mirrors. typically theres little or no coatings on the rear element to reduce it being a partial mirror and typically is so little energy that its not noticable in the photo result. but the long exposure times and many subs being stacked means the shadow grid comes through. Presumably dithering could help especially if you can rotate the sensor in regards to the OTA the reflection will differ when the stars are aligned, and you'll achieve tartan at a fainter level?
not certain, I'm not Scottish.
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Old 15-10-2019, 01:20 PM
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Quote:
Originally Posted by Startrek View Post
I started using a CLS filter with my Canon 600D when in Sydney under Bortle 8 skies but left the subs with a blueish tinge and couldnít totally eliminate it post processing
So I eventually ditched the filter. I use DSS to stack and Startools to remove all types of noise , does a superb job and wonít clip your data
If you use DSS to stack , stack at least 20 or 30 at same exposure length and ISO as your subs and preferably straight after your subs
In DSS under the darks tab ďdo not checkĒ Dark Optimization as it can play havoc with your darks
Also previously mentioned , dithering is a must using DSLRís especially coming into the warmer months
Hope you solve your issues
Good luck
I used one probably three times and I felt it was a backward step. Love to sell it and get back half what I paid for it...how much I can't remember.
Alex
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Old 15-10-2019, 04:34 PM
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Wes, I hope you don't mind, but I did a quick and dirty process of your image. The reason why I suggested that it might've been the filter you're using is because when looking at your file I noticed an imbalance in your channels. This suggests to me that you might have had to remove a colour cast, one possibly produced by your filter. Since the loss of data was in the green channel I'm guessing that the cast was probably a cyan/green colour? Now is it the cause for the grid pattern you're seeing? I'm not sure because after taking a second look I saw that the grid pattern runs throughout all three channels, but it could still amplify the artefact which isn't desirable either.

The good thing is that you've managed to capture a solid amount of data and because of that I was able to reconstruct some of the missing information. Although you can't create what isn't captured you can sometimes synthesise (fake what's missing) which is what I've tried to do here. Essentially I replaced (or guessed) all the tones that I thought were missing from your image to try and balance out your histogram. It's not perfect and by no means scientifically accurate, but hopefully it gives you an idea of what can be done with a channel rebuild. As the others have suggested dithering your subs would really help so, when processing this I attempted a simulated dither to see if I could mask the grid pattern. It's still there no doubt but hopefully not as obvious as before. However, remember I'm doing this as an after thought to an already processed image. If you do this with raw data your results will be a lot better.

I hope this helps.
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Old 15-10-2019, 04:48 PM
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I've down loaded a trial version of Startools and it looks promising in regards to a whole new world of post editing joyfulness. I expect to hopefully start enjoying that part again!! with better results . Thanks for your input one and all.
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Old 15-10-2019, 06:11 PM
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I've also made an attempt using Photoshop 18 cc
Hope it helps, there was a lot of walking noise and banding in this. Is there a depository where you have all the image files we can download and attempt to work with including the darks?
I reckon you used the wrong detection threshold in DSS

As for filters, you are way better off using the Optolong Lpro Filter which is fantastic for light pollution without that cast
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Old 17-10-2019, 06:08 AM
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HI Nikolas ,
Wow ,I'm blown away with generosity ! What you've done is amazing.I do intend to acquire a optolong LP Pro filter I believe we may be attempting to make a silk purse from a sow's ear but here is the link to the folder containing my data set. I have it set on edit . so file can be written to here . Thankyou . https://naa5r8c6.filegear.me:9443/l/r/n/s/r79mmvah. Wes
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Old 17-10-2019, 05:33 PM
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Unfortunately I could only download one image at a time
Can you put them in a google drive and we can try that way?
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Old 17-10-2019, 08:44 PM
gb44 (Glenn)
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colour balance

Hi Wes,
Have you set the Custom White Balance in the camera rather than just using AWB?

GlennB
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Old 18-10-2019, 05:57 AM
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Zubenel (Wes)
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Quote:
Originally Posted by Nikolas View Post
Unfortunately I could only download one image at a time
Can you put them in a google drive and we can try that way?
Sorry Nicolas, unfortunately this is a new thing and one doesnít know what one doesnít know, Iíll look into a google drive. Also my machine is away getting a SD heart transplant 👍🏻😊This should speed processing up somewhat ! So when it comes back Iíll. Have a crack 😉

Glen, Iíve read that the custom whites balance should be set on daylight. Is that correct ? This is what Iíve done . Also reading through the Sequator documentation they donít do all the bias images so I donít either ?🤔
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Old 18-10-2019, 06:03 AM
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Quote:
Originally Posted by sil View Post
Just to chuck an ocelot in with the chickens... the cross hatching I dont think is any of the suggested items. Think in terms of physics. Photons comer through the optical train and exist the OTA/lens and touch nothing until they hit the sensor, then what? they are recorded but the sensor is a flat shiny surface so what happens? the photons reflect back and what do they hit? the last element in the optical train which is smooth and shiny and so reflect back. Yes energy is lost during all this but the photons dont magically get saved into the memory card and cease to exist their energy level is recorded though. some energu is lost through heat when it touched the sensor, some is scattered but the surface of the sensor is a grid of different substances/colours so reflecting the photon back with much less strength then it hits the last optical surface in the optical train and much of the photon travels outwards losing energy but some small amount is reflect back again. think of standing between two parallel mirrors. typically theres little or no coatings on the rear element to reduce it being a partial mirror and typically is so little energy that its not noticable in the photo result. but the long exposure times and many subs being stacked means the shadow grid comes through. Presumably dithering could help especially if you can rotate the sensor in regards to the OTA the reflection will differ when the stars are aligned, and you'll achieve tartan at a fainter level?
not certain, I'm not Scottish.
Sil, Thx man for your detailed exposeí of photon /quantum theory. One thing though , Wont having the chip at prime focus , if there were bouncing photons , would they just reflect back out to space . Eg. Mirrors not lenses. ? Cheers Wes
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