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11-19-2009, 02:41 PM   #31
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DeepSkyStacker for this one.

11-19-2009, 02:49 PM   #32
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As an example of why proper exposure is needed. Here is a under exposed lunar shot. Let's say you took 4 like this and stacked them. Make 4 copies and try it in photomerge in Elements. You can not add what is not there.

Last edited by wildlifephotog; 09-27-2013 at 07:22 AM.
11-19-2009, 02:50 PM   #33
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QuoteOriginally posted by wildlifephotog Quote
DeepSkyStacker for this one.
Many thanks.
I'm trying to learn a bit about long exposures etc.
11-19-2009, 03:00 PM   #34
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Reasons for stacking are improving signal to noise ratio. And to catch shots during the brief periods of clear seeing. The atmosphere is a constant swirling mass. Those air eddies are what cause loss of detail. So if you take 500 shots, you improve your odds of getting those good clear ones. You than stack them. But you can not add brightness by stacking.
It's not like doing multiple exposures on film.

11-19-2009, 03:03 PM   #35
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QuoteOriginally posted by wildlifephotog Quote
As an example of why proper exposure is needed............
Hmmm, so, we should manual focus then after setting the camera for proper exposure, make a x number of images using a remote switch cord, right ?

Did I get it right ?
11-19-2009, 03:06 PM   #36
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Yes, manual focus, test shoot to zero in on exposure, use a remote release. And if you are using a tripod. Check your framing every few shots to make sure the subject stays in the picture. The earth moves.
Oh, and turn off any noise reduction if you can.
11-19-2009, 03:09 PM   #37
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Also, the longer the lens, the faster the subject will go out of view in the finder.
Stop your lens down at least one stop less than max. Here is a 50/1.4 shot wide open. It sucks. The lens suffers from coma wide open. 5 seconds, iso400.
11-19-2009, 03:37 PM   #38
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As soon I have a "star night" I will give it a try

Thanks for the education!

11-19-2009, 03:43 PM   #39
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I'm not much of a teacher. There are a few guys on here much better than I am at this astro stuff.
11-19-2009, 04:12 PM   #40
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QuoteOriginally posted by wildlifephotog Quote
As an example of why proper exposure is needed. Here is a under exposed lunar shot. Let's say you took 4 like this and stacked them. Make 4 copies and try it in photomerge in Elements. You can not add what is not there.
This makes sense to me.

But then in practice, how is the stacking process an alternative to long exposures? If I'm trying to do a shot that requires a 2-minute exposure, but I need to avoid the forced DFS, how can I use multiple 30-second exposures as an alternative? Stacking doesn't seem to be the answer.
11-19-2009, 04:28 PM   #41
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For terrestrial photos it probably would not be of much use. Like a night shot of a city or harbour would not benefit from stacking. It is for bringing out extra detail, not adding brightness.
11-19-2009, 05:32 PM   #42
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Well the K7 is MORE THAN capable of doing star trails.

This is one of my earliest attempts using pretty basic software and about 16 30sec exposures and one dark frame. AND I must add ATROCIOUS lighting conditons.
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11-21-2009, 10:44 PM   #43
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QuoteOriginally posted by PentaxPoke Quote
...Here is a beautiful shot of M42 from Andy Weeks website. It was done with 14, 30-second exposures. That is approximately equivalent to a 7min single exposure:
...
Stacking should work very nicely for meteor showers as well since each meteor event is relatively short.
...
See, no need to get angry or borrow a different camera, just open your mind to new methods.
Good thing I read the 2nd page of this thread. I was about to post "why not stack many many 30-sec exposures", but I wouldn't have done anywhere near as good a job as you.
11-22-2009, 04:44 PM   #44
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If K20D and K7 has DFS does Kx have this problem too? Or it is better for long exposures?
11-22-2009, 06:43 PM   #45
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QuoteOriginally posted by slowdive101 Quote
But then in practice, how is the stacking process an alternative to long exposures? If I'm trying to do a shot that requires a 2-minute exposure, but I need to avoid the forced DFS, how can I use multiple 30-second exposures as an alternative? Stacking doesn't seem to be the answer.
Actually stacking is a great alternative to a single long exposure. About the only thing that it wouldn't work for is fast moving subjects such as traffic and fireworks.

For a 2 minute exposure just take 4 - 30s shots and stack them in photoshop. No need for special registration software if you use a tripod and the scene is not moving (like astro shots).

QuoteOriginally posted by wildlifephotog Quote
For terrestrial photos it probably would not be of much use. Like a night shot of a city or harbour would not benefit from stacking. It is for bringing out extra detail, not adding brightness.
You can use stacking in different ways. The frames can be averaged, summed, or logical add (brightest pixel wins) which is useful for star trails. Below is a shot made up of well over a hundred 30s frames and stacked. Notice how much brighter the stars are compared to a single long exposure. I actually looks much better before it was jpeged to death through the upload process here.
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