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Old 13-05-2008, 07:36 PM
Ian Robinson
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A couple of dumb questions from a 35mm dinosaur who will have a 40D next week.

OK...

I was told my 40D with my chosen two lenses and other bnps will be coming next week ....

I am new to this digital photography thing , 3 questions :

Dark frames : do I do these with a 40D ?

Light and flat frames : what are these , what do they do and how do I do them with a 40D ?

Good digital editing application that is freeware (or comes as a full feature try it out version ....) what do you guys recommend ?
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  #2  
Old 13-05-2008, 07:44 PM
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skwinty (Steve)
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Hi Ian
Darks are exposures with the lens cap on. These should be as long as the exposures you take. This allows you to get a baseline of noisse generated by the camera.
2, Lights are the actual exposures you make to get a picture.
3. Flats are exposures of an evenly illuminated screen , light box or dusk or twilight sky.These enable you to get rid of vignetting and dust donuts etc.

I found that AIP4WIN at USD100 was good value for money as you get a 700 page hard cover text book on astronomical imaging plus the processing software. The text alone IMO is worth the money as it explains all the nitty gritty of calibration and operation of CCD and DSLR cameras.
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Old 13-05-2008, 07:49 PM
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JohnG (John)
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Hi

There is an article in the Projects and Articles section you might want to read:

http://www.iceinspace.com.au/index.p...63,211,0,0,1,0

Cheers

JohnG
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Old 13-05-2008, 08:03 PM
Dennis
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Hi Ian

Just adding to what Steve has written, for darks in particular, I would recommend starting off the “easy” way; let the 40D do the Dark Frames automatically for you, in-camera.

The 40D has several “Custom Function” settings where you can tailor the 40D to how you want to operate.

“Custom Function II -1” or C.Fn II-1 is for managing “Long exposure Noise reduction” and has 3 values:
  • 0: Off (the camera does not perform any “In Camera Noise Reduction” ICNR).
  • 1: Auto (the camera will automatically take an in-camera Dark for exposures longer than 1 second IF it detects noise)
  • 2: On (the camera will automatically take an in-camera Dark for ALL exposures longer than 1 second)
So, if you set C.FN II-1 to “2”, put the 40D on a tripod and take a 30 sec exposure of star trails, when the 30 sec “light exposure” has been taken, the 40D will immediately take a 30 second Dark Frame and subtract it from the preceding 30 sec Light Frame, in-camera.

This means that your 40D will effectively be tied up for 60 seconds. This is ICNR.

It is important to expose your Dark Frame for the same duration and at the same operating temperature as the Light exposure. ICNR achieves these 2 goals.

Cheers

Dennis
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Old 13-05-2008, 08:26 PM
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edwardsdj (Doug)
Doug Edwards

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Hi Ian,

GIMP (Gnu Image Manipulation Program) is the totally free image processing option:

www.gimp.org

It is not easy to learn but there is a free book you can download; much information online; and it has a vast array of features. The colour depth is only 8-bits per channel though.

I'm getting into it more and more every time I use it.

It's not easy to use. It is totally free.

Take care,
Doug
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Old 13-05-2008, 08:59 PM
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Robert_T
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Hi Ian, I've just joined the 40D club too.

Trolling around I found a nice tutorial site on DSLR photography that might answer many of your questions. http://www.astro.shoregalaxy.com/dslr_astro.htm

cheers,

Rob
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Old 13-05-2008, 09:08 PM
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dugnsuz (Doug)
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Quote:
Originally Posted by Robert_T View Post
Hi Ian, I've just joined the 40D club too.

Trolling around I found a nice tutorial site on DSLR photography that might answer many of your questions. http://www.astro.shoregalaxy.com/dslr_astro.htm

cheers,

Rob
That's an excellent link Rob - Cheers
Doug
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Old 13-05-2008, 09:53 PM
Ian Robinson
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Thanks for the answers .... I'll check out those apps and links

Have bookmarked this thread for future reference too.
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