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Old 30-01-2009, 10:22 PM
bloodhound31
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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.
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Old 30-01-2009, 10:52 PM
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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.

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Old 30-01-2009, 11:00 PM
bloodhound31
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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.
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Old 30-01-2009, 11:13 PM
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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.

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Old 31-01-2009, 02:03 PM
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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
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Old 01-02-2009, 03:05 PM
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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.
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Old 01-02-2009, 03:21 PM
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Hi Chris.

Is Photoshop HDR included as part of CS3 Extended or is it a plug-in?
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Old 01-02-2009, 05:16 PM
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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.
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Old 01-02-2009, 05:30 PM
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I have CS3.

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

I also have a trial version of Photomatix 3.1

Thanks.
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Old 01-02-2009, 05:47 PM
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Quote:
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I'm assuming that's: File>Automate>Merge to HDR...
Got it in one!
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Old 01-02-2009, 06:04 PM
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Easy HDR is another option if you don't have PS - there's a freeware version

http://www.easyhdr.com/download.php
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Old 01-02-2009, 06:59 PM
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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.
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