Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Astrophotography and Sketching >> DSLR & Digital Camera Astro Imaging & Processing

Pages: 1 | 2 | (show all)
sternenhimmel
super member


Reged: 06/06/13

Just can't figure out post processing
      #6009965 - 08/06/13 05:29 PM

I've read many tutorials and watched many videos on how people post process their astro images. However, following these techniques I always seem to get a very unsaturated result with lots of noise. I've tried the curves/levels method, alternating between a high pass and adjusting the black point. I've also tried stretching the data just using subsequent level adjustments. I've also tried variations on these techniques and they all seem to produce noisy images with little color data. I then have to bump up the saturation which introduces a lot more noise.

Frankly, it could just be that I lack enough data, or that i shot at too high of an ISO and the noise is a direct result. I've attached the stacked image (TIFF) if anyone wants to take a stab at what little data might be there.

It's a composite of:
23 x 120 second ISO 1600 frames
21 Darks, 20 bias
14 x 120 second ISO 800 frames
8 Darks
1 x 300 second ISO 800 frame
2 Darks

Total time: 1 hr 18 min

UPDATED AGAIN Unaltered Stacked 16-bit TIFF:
https://skydrive.live.com/redir?resid=ADB7CF2255510C5C!109&authkey=!APVix...

The one success I've had is in gradient removal, but the uploaded file is unaltered.

Edited by sternenhimmel (08/07/13 03:12 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
Falcon-
Post Laureate
*****

Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: Just can't figure out post processing [Re: sternenhimmel]
      #6010012 - 08/06/13 05:56 PM

I notice the file is described as "with settings applied" I am guessing you are using Deep Sky Stacker. Would you be able to provide a stack TIFF with the DSS adjustments *not* applied?

Generally speaking DSS's adjustments are not advantageous, they may be why (or part of why) colour is so suppressed.

Edit: Also, could you tell us what lens, what f/-stop the aperture was set to, and what camera you used?

Edited by Falcon- (08/06/13 05:57 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
sternenhimmel
super member


Reged: 06/06/13

Re: Just can't figure out post processing [Re: Falcon-]
      #6010026 - 08/06/13 06:07 PM

The camera was a T1i, unmodded. The lens was a 24-105mm f/4L stopped down to f/5.6 and soht at 105mm.

The file shouldn't have any settings applied. I saved two versions, one with adjustments to the luminosity and color channels, and one where I reset these values and saved the stacked file, which is the file I uploaded. Perhaps it says "with settings applied" because I reset the values?


Post Extras: Print Post   Remind Me!   Notify Moderator  
sternenhimmel
super member


Reged: 06/06/13

Re: Just can't figure out post processing new [Re: sternenhimmel]
      #6010283 - 08/06/13 08:33 PM

To clarify, I'm not looking for someone to do the work for me. I'm happy doing the post processing and I'd love to get a grasp and an intuition for it. I'm really just looking for someone to take a quick look and give me an idea of where my realistic goals for this photo should be.

Post Extras: Print Post   Remind Me!   Notify Moderator  
frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Just can't figure out post processing new [Re: sternenhimmel]
      #6010465 - 08/06/13 10:30 PM Attachment (13 downloads)

I took a go at it, not going to put much time into it, your data is not linear, you need to upload the autosave.tif 32 bit file DSS outputs automatically, anything you save manually in DSS is modified, that being said I no longer use DSS because Pixinsight does a better job with stacking and pre-processing. I could not get any decent color data out of the file provided and its very noisy, Noise reduction is not easy and is best done via methods during capture (sensor cooling, taking darks and using lots of bias frames etc) you image has a big gradent in it that i tried to hide by not streching it as far as it might be able to go. (once again don't want to spend time fixing it)

I'm no expert by any means at post processing but with that data you have provided i can see why you are struggling with it.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Ivo Jager
Vendor ( Star Tools )


Reged: 03/19/11

Loc: Melbourne, Australia
Re: Just can't figure out post processing new [Re: sternenhimmel]
      #6010478 - 08/06/13 10:34 PM Attachment (12 downloads)

Hi,

This is what I came up with in StarTools. It does appear the data has been modified (it has been white balanced at the very least, making true color recovery hard and inhibiting noise reduction), while it also seems to have been stretched in some way (inhibiting again noise reduction and making deconvolution impossible).

Don't despair - it sounds you're doing everything right!

The trouble is that there are some features in DSS that are there to 'help' people get quick results, but in the end they do more harm than good if you really want to get the most out of the data. It can actually be tricky to turn them off I have found - I'm gathering some info and data so I can write a small tutorial/checklist...


Post Extras: Print Post   Remind Me!   Notify Moderator  
mmalik
Postmaster
*****

Reged: 01/13/12

Loc: USA
Re: Just can't figure out post processing new [Re: sternenhimmel]
      #6010498 - 08/06/13 10:39 PM

Couple of pointers:

1. Try following instructions in this... doc if they help.

2. It looks like you have picked a very difficult target to image and to process. Try something more discrete and concise than Andromeda.

3. You may try some unprocessed/combined FITs here... to refine your processing skills.

Hope this helps!


Post Extras: Print Post   Remind Me!   Notify Moderator  
TimN
Pooh-Bah


Reged: 04/20/08

Loc: Ontario, Canada
Re: Just can't figure out post processing [Re: mmalik]
      #6010527 - 08/06/13 10:56 PM

I recommend that you try StarTools. Its easier - was for me - than some of the others and can do a very good job. Its free to try and if you like it its only $60

Post Extras: Print Post   Remind Me!   Notify Moderator  
sternenhimmel
super member


Reged: 06/06/13

Re: Just can't figure out post processing [Re: mmalik]
      #6010539 - 08/06/13 11:02 PM

These are 3 excellent responses that I would like to address individually:

Frito and Ivo (and Falcon): You all appear to be correct. I realized earlier that when I opened the Autosave file that the curve was linear, whereas when I opened the TIFF file I saved, the curve was non-linear. I was unaware that the DSS defaults were non-linear and this does explain a lot.

Frito: There is a large gradient as a result of the wide field and that the object started near the horizon during the beginning of imagining. The good news is that my trial version of GradientXTerminate seems to do an excellent job at removing said gradient.

Ivo: Wonderful. I'm glad to see that, even working with non-linear data, you were able to extract significant detail and obtain good color. I'm unfamiliar with StarTools though...

mmalik: That's quite the guide you've got there! Are ImagePlus and PixInsight preferred tools for the people doing serious astrophotography? What makes Adromeda a difficult target? I always thought it would be an easy target due to it's large size and relative brightness.


Post Extras: Print Post   Remind Me!   Notify Moderator  
frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Just can't figure out post processing [Re: sternenhimmel]
      #6010556 - 08/06/13 11:12 PM Attachment (8 downloads)

Oh i'm quite familiar with gradents caused by light pollution, deal with it all the time on my own images. gradentXterminator is a great plugin for photoshop, i used up my trial and decided not to buy it because i'm no longer using photoshop for my astro stuff, pixinsight is just plain superior. Startools is a great easier to use cheaper alternative to both, i played with it, was set back at first at how basic it seemed but it can do some great things for sure but with pixinsights all inclusive and mass array of tools i'm definately going the pixinsight route once my trial licence is up, its well worth the 200 dollars esp if one does not own photoshop to begin with (and i do, but the plugins to make photoshop useful and eaiser on you quickly add up to 200 dollars)

the issue with andromeda is the color, its pretty subtle. here is a good comparison for you below is my most recent andromda i imaged last friday from a DARK site (bortle 2-3)



and attached was imaged from a orange zone "darker site" i often go to. granted i got much more data from the dark site and it was also more well placed when i imaged it from there it still shows the drastic differnece. its not as easy of a target as one would think, M13 would be something i would call an easy target but for really widefield like you are doing you should hit up sections of the milky way this time of the year i would think.

Edited by frito (08/06/13 11:14 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
mmalik
Postmaster
*****

Reged: 01/13/12

Loc: USA
Re: Just can't figure out post processing [Re: sternenhimmel]
      #6010562 - 08/06/13 11:15 PM

"Are ImagePlus and PixInsight preferred tools for the people doing serious astrophotography?"

Yes! You could get their trial versions free to learn.

"What makes Andromeda a difficult target? I always thought it would be an easy target due to it's large size and relative brightness."

Quite the contrary; Andromeda's dynamic range and it's distribution makes it difficult to acquire/process properly. Try something like dumbbell nebula to practice. Thx


Post Extras: Print Post   Remind Me!   Notify Moderator  
sternenhimmel
super member


Reged: 06/06/13

Re: Just can't figure out post processing new [Re: mmalik]
      #6010584 - 08/06/13 11:27 PM

I'm convinced, I'll take a look at PixInsight. PS was just familiar to me and I already had it, so I started there. I was also very encouraged by the impressive results I was seeing in various tutorials.

Anyway, I'm now working with a linear image and am already getting better results! I replace the TIFF file in the original thread with the unaltered version I'm using now, just in case anyone else wants to take a stab.
https://skydrive.live.com/redir?resid=ADB7CF2255510C5C!108&authkey=!AH_hR...

Edited by sternenhimmel (08/06/13 11:45 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Just can't figure out post processing new [Re: sternenhimmel]
      #6010589 - 08/06/13 11:30 PM

If you get a Pixinsight trial i highly recommend harry's astro shed's tutorials, they will get you started.

http://www.harrysastroshed.com/pixinsighthome.html


Post Extras: Print Post   Remind Me!   Notify Moderator  
sternenhimmel
super member


Reged: 06/06/13

Re: Just can't figure out post processing new [Re: frito]
      #6010594 - 08/06/13 11:33 PM

Awesome frito, thanks!

Also beautiful shots of Adromeda you've got there. Clearly what I need to do is invest in some better equipment .


Post Extras: Print Post   Remind Me!   Notify Moderator  
frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Just can't figure out post processing new [Re: sternenhimmel]
      #6010598 - 08/06/13 11:37 PM

i'm using a pretty basic setup to be honest, low amount of money invested thus far.

66mm Semi-APO scope
Canon 350D (Rebel XT)
used CG-5 AS-GT mount unguided.

thats it. total investment under 1k. starting off with just a DSLR and a lens is easier though but if you do step up to using a telescope start with a small widefield APO refractor like mine, it will help a lot, your camera alone on my setup would increase the quality of my images i have no doubt due to its higher resolution.


Post Extras: Print Post   Remind Me!   Notify Moderator  
sternenhimmel
super member


Reged: 06/06/13

Re: Just can't figure out post processing new [Re: frito]
      #6010626 - 08/06/13 11:52 PM

I don't want to derail this read too much, but I will say this:

I own an Orion 8" f/4 Newtonian, but it lives at my parents' place in Arizona. That kind of scope would probably require guiding and a sturdy mount. Plus, it's not exactly the most portable scope.

I have been looking at the Stellarvue 70ED http://www.astropix.com/HTML/I_ASTROP/EQ_TESTS/SV70ED.HTM, which would be comparable to the scope you're using. Part of me wonders whether or not I could get away with 1 or 2 minute exposures at that focal length if I improve the performance of my barn door tracker...


Post Extras: Print Post   Remind Me!   Notify Moderator  
frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Just can't figure out post processing new [Re: sternenhimmel]
      #6010643 - 08/07/13 12:02 AM

your talking a pretty big weight and balance differience going from a DSLR w/ lens to a small refractor with lens, I could be wrong but i've never heard or seen anyone try to use a barn door tracker with an actual telescope before. I honestly thing it would be more trouble than its worth, just get a used CG-5 they can be had for under 400 these days, with an autoguider it would not be out of the question that you could image on a CG-5 with your 8" F/4 but an 8" SCT is a better route to go at that size.

Post Extras: Print Post   Remind Me!   Notify Moderator  
frito
Pooh-Bah


Reged: 10/05/12

Loc: Fremont, CA
Re: Just can't figure out post processing new [Re: frito]
      #6010645 - 08/07/13 12:03 AM

oh and you can't derail your own thread, if anyone derailed it it was me bringing up equipment LOL.

Post Extras: Print Post   Remind Me!   Notify Moderator  
srosenfraz
Post Laureate
*****

Reged: 03/06/11

Loc: United States
Re: Just can't figure out post processing new [Re: frito]
      #6010739 - 08/07/13 01:40 AM

Here's a very quick and dirty processing of your data in Photoshop:



Full Resolution version. If you're interested to see my layers, my Photoshop .psd available here (25MB)

It still looks to me like your stacked tif has had a prior stretch applied to it. Nonetheless, your data seems quite usable. A more careful processing could probably produce a very nice image.

Edited by srosenfraz (08/07/13 01:42 AM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
mmalik
Postmaster
*****

Reged: 01/13/12

Loc: USA
Re: Just can't figure out post processing new [Re: sternenhimmel]
      #6010742 - 08/07/13 01:43 AM

Quote:

PS was just familiar to me and I already had it, so I started there.




You can and will still be using PS, just little differently when you use PI or IP. A combinant processing technique here.... Thx


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1 | 2 | (show all)


Extra information
18 registered and 25 anonymous users are browsing this forum.

Moderator:  Dave M, fishonkevin, WOBentley, tecmage 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 612

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics