Deminishing returns.....

Started 4 months ago | Discussions
thinker Regular Member • Posts: 226
Re: Deminishing returns.....

Astrozoid wrote:

thinker wrote:

Astrozoid wrote:

Kemo-sabe wrote:

Astrozoid, you are correct in your analysis. The images were shot in Bortle 9 sky and consist of 193 5 minute subs with a Canon FD 800mm f5.6l lens with a Canon 5D MKIII at iso400 incorporating an Optolong L-eNhance dou-band 2" drop-in

[1a]

filter. My guide scope consist of a DIY Canon FD 300mm f4.0l lens coupled to a QHY5LII-C guide camera. The Mount is an iOptron CEM25P with ADM side by side saddle and iPolar scope for polar alignment. I have Pegasus power distribution for the mount/equipment and dual Pegasus focus controllers for remote focusing the primary optics and guide-scope.

I am a newbie to processing astro images. It has has taken me more than 1 year to automate and dial-in the hardware software aspects of astro imaging and learn the nuances of the system.

However, astro processing is another story. I was to embarrassed by my pitiful results to post such a sad image in the light of so many awesome images that I have seen on this forum. Pride is a terrible thing.

My son suggested that I post the image to see if I could get some advice and input on what I am doing wrong in my processing workflow. Or, is this the best that one might expect from Bortle 9 skies with the optical equipment I am using or a combination of both?

I am using Clarke's methodology of in camera dark frame extraction for the

[2a]

subs.Using Clarke's Methodology the subs actually take 10 minutes to shoot per sub. I use Sequator and/or DSS for stacking. PS RC-Astro filter GradientXterminator to remove gradients. Then RNC stretch or PS to stretch. StarTools or DxO PhotoLab4 Post Processing.

I have been experimenting with Canon's DPP4 RAW processor to process and convert the RAW subs to TIFF prior to stacking with varying results. In an attempt to pull more fine detail from the subs.

Post a link to the raw, linear stack and we'll see if there is more there to be brought out in processing.

Jerry

Could you please comment on the use of ISO400 with 7.8 electrons read noise vs ISO3200 (2.4 electrons) or even ISO6400/ISO12800 (with his filter)?

And the use of in-camera dark frame subtraction, as a misunderstanding of Roger's "On-Sensor Dark Current Suppression Technology", besides doubling imaging time?

A lower read noise would only help you if you were shooting under truly dark skies or with a narrowband filter.

[1b]

Once your exposure is sky-noise limited, and not read-noise limited, you can pretty much totally forget about read noise, it is trivial.

With a really bright sky, you don't have to worry about read noise, so use a low ISO. Just expose so the peak of the histogram on the back of the camera is 1/3 of the way over from the left. Then turn off LENR and shoot as many frames as you can. Dithering will also help tremendously.

Personally, I have never recommended LENR - except for single frames.

Photons are only recorded when the camera is open to the sky. Photons are the only thing that make up the signal half of the signal-to-noise ratio. There is no other way to improve the signal. But you could have recorded twice as many photons and doubled your signal if you had shot lights continusously instead of wasting half of your clearsky time shooting LENR in-camera darks.

So I advise to shoot darks on a cloudy night in your garage under similar temperatures. Then you can shoot darks all night long and create a really good master dark frame.

When you use LENR you get a double whammy hit because not only have you lost half the signal you could have recorded, you are adding noise in each dark that you shoot in the camera. You would add a lot less noise with a good master dark.

[2b]

LENR is not the same thing as on-sensor dark suppression technology.

And, most importantly, dark suppression technology is not removing thermal signal. It just removes the artifacts, like bright pixels, from thermal (dark) signal. It does not remove the shot noise associated with the dark signal. The only way to deal with this is by collecting more photons to improve the signal half of the signal-to-noise ratio.

Jerry

Thank you for the information!

When OP uses [1a] an Optolong L-eNhance filter which I understand is a duo narrowbandfilter, and what you say [1b] about lower read noise would help with narrowband filter, wouldn't higher ISO help OP? Or is Optolong L-eNhance not narrow enough? (filter curve below)

Combining this (above) with the fact that OP uses LENR [2a] with your [2b] statement about adding noise in each dark shot in camera, wouldn't this suggest that using, say, ISO3200 and avoid using LENR lead to OP having potential for much improved result with his gear? (the subject of this thread)

Sorry, not my intention to nag you, I'm an (eternal) beginner ..

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(Harvey) - Jane, I've been thinking...
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OP Kemo-sabe Junior Member • Posts: 39
Re: Deminishing returns.....

Is there a preferred better method to upload 200 RAW file vs. Google Drive? I am new to this.

I am in the process of uploading to Google Drive.  So please bear with me, this is a time consuming adventure. lol.....

Astrozoid
Astrozoid Contributing Member • Posts: 846
Re: Deminishing returns.....

thinker wrote:

Thank you for the information!

When OP uses [1a] an Optolong L-eNhance filter which I understand is a duo narrowbandfilter, and what you say [1b] about lower read noise would help with narrowband filter, wouldn't higher ISO help OP? Or is Optolong L-eNhance not narrow enough? (filter curve below)

With his camera, higher ISO produces lower read noise.

Lower read noise lets you use shorter exposures to reach a sky-noise limited exposure.

Narrowband filters don't let in much light, so to reach sky-noise limit for the sky background (not the nebula lines which the filter are passing) you need really long exposures.

The L-enhance bandpasses are narrow, but not as narrow as a true narrowband filter.

With a lot of light pollution, all of this becomes moot.  The sky noise totally overwhelms readout noise so you can use a lower ISO with a high readout noise.

Once your exposure is sky-noise limited, increasing the ISO only reduces the dynamic range.

So with bright skies, where you don't have to worry about being sky-noise limited, you should use a low ISO to get as much DR as you can.

There is an alternative argument to use a higher ISO for exceedingly faint objects, but I won't get into there here.

Combining this (above) with the fact that OP uses LENR [2a] with your [2b] statement about adding noise in each dark shot in camera, wouldn't this suggest that using, say, ISO3200 and avoid using LENR lead to OP having potential for much improved result with his gear? (the subject of this thread)

No. As I mentioned, all you would be doing would be sacrificing dynamic range. You don't need extrememly low read noise in bright skies. I certainly recommend not using LENR. And I recommend a lower ISO if you are guiding and can track accurately.

Sorry, not my intention to nag you, I'm an (eternal) beginner ..

No problem.

Jerry

Astrozoid
Astrozoid Contributing Member • Posts: 846
Re: Deminishing returns.....

Kemo-sabe wrote:

Is there a preferred better method to upload 200 RAW file vs. Google Drive? I am new to this.

I am in the process of uploading to Google Drive. So please bear with me, this is a time consuming adventure. lol.....

I don't want 200 raw files.

I want your raw, linear, 16-bit stack, before you do anything else to it.

That should be one file.

Jerry

OP Kemo-sabe Junior Member • Posts: 39
Re: Deminishing returns.....

Astrozoid wrote:

Kemo-sabe wrote:

Is there a preferred better method to upload 200 RAW file vs. Google Drive? I am new to this.

I am in the process of uploading to Google Drive. So please bear with me, this is a time consuming adventure. lol.....

I don't want 200 raw files.

I want your raw, linear, 16-bit stack, before you do anything else to it.

That should be one file.

Jerry

OOpppsss.....

Do you want the stack in Sequator or Dss?

Astrozoid
Astrozoid Contributing Member • Posts: 846
Re: Deminishing returns.....

Kemo-sabe wrote:

Do you want the stack in Sequator or Dss?

DeepSkyStacker.

Save as type: TIFF image (16 bit/ch)

No compression.

Most importantly: Embed adjustments in the saved image but do not apply them.

Jerry

OP Kemo-sabe Junior Member • Posts: 39
Re: Deminishing returns.....

Astrozoid wrote:

Kemo-sabe wrote:

Do you want the stack in Sequator or Dss?

DeepSkyStacker.

Save as type: TIFF image (16 bit/ch)

No compression.

Most importantly: Embed adjustments in the saved image but do not apply them.

Jerry

https://www.flickr.com/photos/master_of_light_studios/50564855282/in/dateposted-public/

DSS Stack

https://www.flickr.com/photos/master_of_light_studios/50563999983/in/dateposted-public/

Sequator stack

Astrozoid
Astrozoid Contributing Member • Posts: 846
Re: Deminishing returns.....

Kemo-sabe wrote:

https://www.flickr.com/photos/master_of_light_studios/50564855282/in/dateposted-public/

DSS Stack

https://www.flickr.com/photos/master_of_light_studios/50563999983/in/dateposted-public/

Sequator stack

The DSS stack is a jpeg.

I can't do anything with that.

The Sequator stack is already stretched.

I need a 16-bit linear TIFF file from DSS with the parameters I mentioned before.

Jerry

OP Kemo-sabe Junior Member • Posts: 39
Re: Deminishing returns.....

Astrozoid wrote:

Kemo-sabe wrote:

https://www.flickr.com/photos/master_of_light_studios/50564855282/in/dateposted-public/

DSS Stack

This is a jpeg.

I can't do anything with that.

Jerry

Got it.  I get hung when trying to upload TIFFs on DPR.  Flickr is converting the Tiff files to JPEGs.  So I will upload the TIFFs to my Google Drive and give permissions to download.  Away I go to get it done....

Alen K Senior Member • Posts: 1,134
Re: Deminishing returns.....

Astrozoid wrote:

When you use LENR you get a double whammy hit because not only have you lost half the signal you could have recorded, you are adding noise in each dark that you shoot in the camera. You would add a lot less noise with a good master dark.

I don't understand this. Please elaborate. If I take N light frames with LENR on (generally a bad idea, I agree), I will be using N dark frames, one for each light. Mathematically, there should be no difference between averaging N frames, each with a dark pre-subtracted, and averaging N frames then subtracting the average of N dark frames (the master dark). That does assume the camera is doing dark-frame subtraction properly and that is not always the case. I'm also not sure how stacking methods like median combine would change the math.

OP Kemo-sabe Junior Member • Posts: 39
Re: Deminishing returns.....

How do I upload a TIFF file?

Astrozoid
Astrozoid Contributing Member • Posts: 846
Re: Deminishing returns.....
1

Alen K wrote:

Astrozoid wrote:

When you use LENR you get a double whammy hit because not only have you lost half the signal you could have recorded, you are adding noise in each dark that you shoot in the camera. You would add a lot less noise with a good master dark.

I don't understand this. Please elaborate. If I take N light frames with LENR on (generally a bad idea, I agree), I will be using N dark frames, one for each light. Mathematically, there should be no difference between averaging N frames, each with a dark pre-subtracted, and averaging N frames then subtracting the average of N dark frames (the master dark).

Yea, except for one thing.

I can construct a master dark out of as many subs as I like when I shoot darks in my garage.

I don't have to limit it to the same number as the number of lights.

If you shoot 16 lights with 16 darks, you will inject X amount of dark-frame subtraction calibration noise. With 64 darks, I will only inject 1/2 as much.

So, separate darks vs LENR darks will inject less noise to the final stack.

Jerry

swimswithtrout Veteran Member • Posts: 3,777
I Guaranty There's a Whole Lot More There...

This is just a case of not knowing how to PP an image...

Upload your stacked TIF to Dropbox or even Google drive

Alen K Senior Member • Posts: 1,134
Re: Deminishing returns.....

Astrozoid wrote:

Alen K wrote:

Astrozoid wrote:

When you use LENR you get a double whammy hit because not only have you lost half the signal you could have recorded, you are adding noise in each dark that you shoot in the camera. You would add a lot less noise with a good master dark.

I don't understand this. Please elaborate. If I take N light frames with LENR on (generally a bad idea, I agree), I will be using N dark frames, one for each light. Mathematically, there should be no difference between averaging N frames, each with a dark pre-subtracted, and averaging N frames then subtracting the average of N dark frames (the master dark).

Yea, except for one thing.

I can construct a master dark out of as many subs as I like when I shoot darks in my garage.

I don't have to limit it to the same number as the number of lights.

Of course.

If you shoot 16 lights with 16 darks, you will inject X amount of dark-frame subtraction calibration noise. With 64 darks, I will only inject 1/2 as much.

So, separate darks vs LENR darks will inject less noise to the final stack.

Only true if you shoot fewer lights than you want to use for darks. And not so in this case. The OP shot 193 lights, hence because of LENR 193 darks. That's excessive, IMO, but the result will not be worse with respect to injected random noise than shooting a bunch of darks later unless you go crazy and shoot hundreds of them. I don't know how many darks you usually use, but I see that many people use as few as 20 and usually no more than 50. In that case, the OP's 193 will technically inject less random noise. But the difference will be VERY small, certainly not worth the huge waste of time that could have been spent taking more light frames.

So, I don't see this as a "double whammy hit." But the single whammy hit is bad enough!

OP Kemo-sabe Junior Member • Posts: 39
Re: I Guaranty There's a Whole Lot More There...

swimswithtrout wrote:

This is just a case of not knowing how to PP an image...

Upload your stacked TIF to Dropbox or even Google drive

I have already uploaded to my Google drive and my DropBox. In order for someone to be able to access the file I need an email address to send a invite notification that they have permissions to edit/download the file. Google drive will only send notifications to share the file to an email address. When I try to enter a user's name Google Drive won't allow me to do so. I get an error that says not a proper email address entered.

I agree that post processing astro images is not my forte. I have been attempting to follow online workflows to no avail. However, it could also be that I am imaging from a Bortle 9 sky in combination with my lack of experience processing astro images as well.  This is YTBD and I need to rely on the greater experience and advise from seasoned astrophotographers that are willing to help/advise a newbie (me).

ATPIT I'm starting to believe that the only thing that I have done successfully is the integration and automation of the hardware and software to be able to guide and take long exposure DSO images.

Alen K Senior Member • Posts: 1,134
Re: Deminishing returns.....

Kemo-sabe wrote:

Astrozoid wrote:

Kemo-sabe wrote:

https://www.flickr.com/photos/master_of_light_studios/50564855282/in/dateposted-public/

DSS Stack

This is a jpeg.

I can't do anything with that.

Jerry

Got it. I get hung when trying to upload TIFFs on DPR. Flickr is converting the Tiff files to JPEGs. So I will upload the TIFFs to my Google Drive and give permissions to download. Away I go to get it done....

Re the Sequator stack, you can set Sequator to give linear TIFF output. You do have to set the option however; it normally applies a standard SRGB screen-transfer curve.

OP Kemo-sabe Junior Member • Posts: 39
Re: Deminishing returns.....

Alen K wrote:

Kemo-sabe wrote:

Astrozoid wrote:

Kemo-sabe wrote:

https://www.flickr.com/photos/master_of_light_studios/50564855282/in/dateposted-public/

DSS Stack

This is a jpeg.

I can't do anything with that.

Jerry

Got it. I get hung when trying to upload TIFFs on DPR. Flickr is converting the Tiff files to JPEGs. So I will upload the TIFFs to my Google Drive and give permissions to download. Away I go to get it done....

Re the Sequator stack, you can set Sequator to give linear TIFF output. You do have to set the option however; it normally applies a standard SRGB screen-transfer curve.

I have seen that in color space but I've never used it.  I typically set the color space to aRGB.

1llusive
1llusive Veteran Member • Posts: 3,297
Re: I Guaranty There's a Whole Lot More There...

Kemo-sabe wrote:

swimswithtrout wrote:

This is just a case of not knowing how to PP an image...

Upload your stacked TIF to Dropbox or even Google drive

I have already uploaded to my Google drive and my DropBox. In order for someone to be able to access the file I need an email address to send a invite notification that they have permissions to edit/download the file. Google drive will only send notifications to share the file to an email address. When I try to enter a user's name Google Drive won't allow me to do so. I get an error that says not a proper email address entered.

Just share the link with the setting: "anyone with the link". No email required.

 1llusive's gear list:1llusive's gear list
Nikon Z6 II Sigma 100-400mm F5-6.3 Nikon Z 24-70mm F4 Nikon Z 85mm F1.8 +1 more
OP Kemo-sabe Junior Member • Posts: 39
Re: I Guaranty There's a Whole Lot More There...

1llusive wrote:

Kemo-sabe wrote:

swimswithtrout wrote:

This is just a case of not knowing how to PP an image...

Upload your stacked TIF to Dropbox or even Google drive

I have already uploaded to my Google drive and my DropBox. In order for someone to be able to access the file I need an email address to send a invite notification that they have permissions to edit/download the file. Google drive will only send notifications to share the file to an email address. When I try to enter a user's name Google Drive won't allow me to do so. I get an error that says not a proper email address entered.

Just share the link with the setting: "anyone with the link". No email required.

Here is the link to the M42 subs image stacked in DSS. I hope this link works.

https://drive.google.com/file/d/1DJfLhN8l0tr-hesXwhQB8ZF7mdpcXT3S/view?usp=sharing

How rude of me. I forgot to say Thank You, 1llusive.

Astrozoid
Astrozoid Contributing Member • Posts: 846
Re: Deminishing returns.....

Alen K wrote:

Only true if you shoot fewer lights than you want to use for darks.

Yes, that is my exact point.

Normally, it is easy to shoot more darks than lights.

I usually use at least 64.

Jerry

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