#1  
Old 30-01-2009, 09:22 PM
bloodhound31
Registered User

bloodhound31 is offline
 
Join Date: Aug 2006
Posts: 4,628
Avoiding image burn-out

I am currently in the obs taking 90 second exposures through the Orion Starshoot III at M42.

This screenshot is the resulting single frame unprocessed out of the camera.

Once I stack ten or so of these with their darks and flats, I can imagine the core will be unrecognizable.

How does one image the extremeties of the nebula, while maintaining the detail in the core?

I will ask in a couple of places and see what different technique answers I get from people.

Baz.
Attached Thumbnails
Click for full-size image (untitled.JPG)
78.4 KB35 views
Reply With Quote
  #2  
Old 30-01-2009, 09:52 PM
Matty P's Avatar
Matty P (Matt)
Star Struck

Matty P is offline
 
Join Date: Nov 2007
Location: Canberra
Posts: 2,797
Hi Baz,

The way to do it is take series of shorter exposures that do not over expose the core. What you do is use the shorter exposures as a mask on top of the longer exposures. The result is a properly exposed image showing the full dynamic range of the object.

There is a great tutorial on how to do this but I can't find the link. I'll see if I can find it for you.

Reply With Quote
  #3  
Old 30-01-2009, 10:00 PM
bloodhound31
Registered User

bloodhound31 is offline
 
Join Date: Aug 2006
Posts: 4,628
Thanks Matt! Who says the young can't teach us old dogs new tricks?

I have reached the middle point in my life where the new stuff young people have to pass on is nearly as important as the experience the old folks have to offer!

Onya mate. I look forward to that link if you can find it.

Baz.
Reply With Quote
  #4  
Old 30-01-2009, 10:13 PM
Matty P's Avatar
Matty P (Matt)
Star Struck

Matty P is offline
 
Join Date: Nov 2007
Location: Canberra
Posts: 2,797
Quote:
Originally Posted by bloodhound31 View Post
Thanks Matt! Who says the young can't teach us old dogs new tricks?

I have reached the middle point in my life where the new stuff young people have to pass on is nearly as important as the experience the old folks have to offer!

Onya mate. I look forward to that link if you can find it.

Baz.
LOL... It scary how much I've learnt in the past year since starting astrophotography and I'm greatful that I can teach the older generation some tricks.

You're lucky Baz, I found the link. Took me awhile.

Here you go.

http://www.astropix.com/HTML/J_DIGIT/LAYMASK.HTM

It's fairly invovled the first time you try it but its gets easier once you get used to the technique.

Reply With Quote
  #5  
Old 31-01-2009, 01:03 PM
Quark's Avatar
Quark (Trevor)
Registered User

Quark is offline
 
Join Date: Apr 2008
Location: Broken Hill NSW Australia
Posts: 4,104
Hi Barry and Matt,

I also have been wondering how to go about processing M42 and other similar objects that share such contrasting regions.

That is a top link Matt, found it very enlightening.
I think that old dogs can learn new tricks, it's just a matter of remaining open to this era of technological change we are in.

Regards
Trevor
Reply With Quote
  #6  
Old 01-02-2009, 02:05 PM
Omaroo's Avatar
Omaroo (Chris Malikoff)
Let there be night...

Omaroo is offline
 
Join Date: Aug 2006
Location: Hobart, TAS
Posts: 7,639
Matty's very correct Barry. Lots of short exposures does the trick. There's also HDR. I took 10x5 sec frames, 10x10 sec, 10x20sec and 10x60sec frames as well as 2x120sec and 2x360sec frames all merged in Photoshop HDR to from the final image. It's resolved right to the core and there is still a reasonable amount of nebulous area showing. The longer frames all had the core badly burned out, but the HDR ptocess understood this and the result is pretty reasonable.
Attached Thumbnails
Click for full-size image (fourtytwo.jpg)
183.7 KB32 views
Reply With Quote
  #7  
Old 01-02-2009, 02:21 PM
matt's Avatar
matt
6000 post club member

matt is offline
 
Join Date: Oct 2005
Location: Launceston, Australia
Posts: 6,570
Hi Chris.

Is Photoshop HDR included as part of CS3 Extended or is it a plug-in?
Reply With Quote
  #8  
Old 01-02-2009, 04:16 PM
Omaroo's Avatar
Omaroo (Chris Malikoff)
Let there be night...

Omaroo is offline
 
Join Date: Aug 2006
Location: Hobart, TAS
Posts: 7,639
It's part of CS3 Matt.

Of course there are other HDR processors out there like EasyHDR that work very well if you don't have a fully-fledged version of Photoshop.
Reply With Quote
  #9  
Old 01-02-2009, 04:30 PM
matt's Avatar
matt
6000 post club member

matt is offline
 
Join Date: Oct 2005
Location: Launceston, Australia
Posts: 6,570
I have CS3.

I'm assuming that's: File>Automate>Merge to HDR...

I also have a trial version of Photomatix 3.1

Thanks.
Reply With Quote
  #10  
Old 01-02-2009, 04:47 PM
Omaroo's Avatar
Omaroo (Chris Malikoff)
Let there be night...

Omaroo is offline
 
Join Date: Aug 2006
Location: Hobart, TAS
Posts: 7,639
Quote:
Originally Posted by matt View Post

I'm assuming that's: File>Automate>Merge to HDR...
Got it in one!
Reply With Quote
  #11  
Old 01-02-2009, 05:04 PM
peter_4059's Avatar
peter_4059 (Peter)
Big Scopes are Cool

peter_4059 is offline
 
Join Date: Jun 2007
Location: SE Tasmania
Posts: 4,532
Easy HDR is another option if you don't have PS - there's a freeware version

http://www.easyhdr.com/download.php
Reply With Quote
  #12  
Old 01-02-2009, 05:59 PM
Bassnut's Avatar
Bassnut (Fred)
Narrowfield rules!

Bassnut is offline
 
Join Date: Nov 2006
Location: Torquay
Posts: 5,064
Having just had a 1st poke at M42 myself, it bought home the reality that one MUST get the hang of layer masks in PS (with varing exposure times in this case), once you get over that hurdle, its a doddle, and they are sooo usefull for selective sharpening etc too, lots of things.

Without learning this, the astroimaging experience will eventually hit a brick wall, its an essential skill.

And, PS is a must have, simple as that.
Reply With Quote
Reply

Bookmarks

Thread Tools
Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +10. The time is now 10:41 AM.

Powered by vBulletin Version 3.8.7 | Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Advertisement
Bintel
Advertisement
Testar
Advertisement