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(again)noise in long exposures or about almost "bulb mode"

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Offline jetzt

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(again)noise in long exposures or about almost "bulb mode"
« on: 07 / April / 2008, 09:56:39 »
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So after I think "Cutts"-results I tried long exposures again.
My results are not so amazing.
(The painting, which should mean "hi there" is really only for testing, no ad or anything :D)
Does anybody know what I forgot? Or do I have to live with that noise and try to reduce it a bit?

first the darkframes jpg:


here is it from raw(wrong wb or I lost some data while converting):


one of the 65sec-shots I combined to the next image:


the in camera developped jpeg of the WAV That contains the summed data of 6 RAWs


the pc developped WAV(with the same converting problems(I assume gimp colorspace of 8 and the saved 16 bit from the raw converter should have changed to 8bit)


the result of 5 times applied BackFrameNr on jpegs (in beetween savings in TIF)


the result of 2 times BlackFrameNR on RAWs(again with the converting-errors)


I finally tried to substrakt in gimp, because it's much faster:(layer mod substract)


So what did I forget/I'm sure I made a fault?

Thanks for any replies,
and sorry for that my results are not good to compare jpeg vs RAW.
But I'll try any advice sooner or later. :D
« Last Edit: 12 / April / 2008, 13:28:44 by jetzt »
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Offline Barney Fife

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Re: (again) noise in longer exposures
« Reply #1 on: 07 / April / 2008, 11:10:48 »
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« Last Edit: 22 / April / 2008, 16:37:04 by Barney Fife »
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Re: (again) noise in longer exposures
« Reply #2 on: 07 / April / 2008, 13:12:46 »
Ah, one hint already, I let the camera "get used to enviroment conditions" before starting it up (about 5 to 10 mins.).
But I took the darkframe first, immediatly after startup, however I took it with the exact same Settings.
I read something about that amp-glow already, but as it seems to me that I'm the first early starter on "alzheimer"...

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Lots of things to know and pay attention to. You're treading into unknown territory into how to deal with all these many variables that we have to play with now.
I didn't expect any instant results(you should never), but when you do not play with/try something, you won't learn it.

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Neat though. Smiley
Wow, that somehow tells me you downloaded the pictures, (I thought you have dail-up?).
Thanks for your reply,
jetzt
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Offline Barney Fife

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Re: (again) noise in longer exposures
« Reply #3 on: 07 / April / 2008, 13:31:09 »
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« Last Edit: 22 / April / 2008, 16:37:29 by Barney Fife »
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Re: (again) noise in longer exposures
« Reply #4 on: 07 / April / 2008, 13:35:41 »
So perhaps I'll try this night. but I leave on Wednesday so I'll have to move that topic to the weekend.

Maybe I have to build a new "lens-cap, as a710 has none.".
You don't want to see my quick and dirty assembly. :haha
« Last Edit: 07 / April / 2008, 13:38:59 by jetzt »
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Offline Barney Fife

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Re: (again) noise in longer exposures
« Reply #5 on: 07 / April / 2008, 13:49:41 »
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« Last Edit: 22 / April / 2008, 16:37:49 by Barney Fife »
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Offline jetzt

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Re: (again) noise in longer exposures
« Reply #6 on: 12 / April / 2008, 13:26:14 »
I gave it a try with in-camera-NR on, as I didn't want to miss that one on my journey.
I didn't have a tripod, so some boxes were used ;).
It took not only 65sec for the exposure but I suppose about 2 mins, cause there was the string "Daten werden bearbeitet"->
"Data is being processed" on the screen.
Anyway the scene didn't change and so that was equal.(I know it is already on the wiki, but to say it clearly for someone who searches, with lowest iso override, iso30 in my case, the internal NR is almost sufficent.)
I didn't try hdr, cause we were running out of time, but I think the panorama doesn't look that bad either.

As mentioned I didn't do anything for my original idea of an almost "bulb-mode" with less noise.
But I hope I will get much more in the nearest future.
But I have no idea where these small black spots come from, sharpening?

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Offline PhyrePhoX

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Re: (again)noise in long exposures or about almost "bulb mode"
« Reply #7 on: 12 / April / 2008, 13:42:53 »
65 seconds exposure + 65 seconds exposure with closed shutter = noise reduction.you can actually move the cam and stuff it into your pocket as soon as "data is being processed" is displayed.
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Offline jetzt

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Re: (again)noise in long exposures or about almost "bulb mode"
« Reply #8 on: 13 / April / 2008, 06:31:58 »
Quote from: PhyrePhoX on 12 / April / 2008, 13:42:53
65 seconds exposure + 65 seconds exposure with closed shutter = noise reduction.you can actually move the cam and stuff it into your pocket as soon as "data is being processed" is displayed.
I can't I have a small bag :haha. You're right with what the exposure duration consists of.

Here are my examples, I didn't plan anything, so I forgot to also try it with in-camera NR :( for comaring the results.
I didn't apply any further post processing, however I summed the jpegs and substracted the Darkframes with gimp just
to save sd-card lifetime.(Please don't start a discussion about what the best image manipulation program is.)
Here are some image parts:
First the Result of 3 summed RAWs with 3 times substracted a darkframe, take AFTER the actual shots.


Here is how it would look like with 3xsubstraction of a darkframe taken BEFORE the actual shots.


As expected the one above isn't that much better that this one here without any NR.


I thought 3 Images would be enough, as we really had very bright moonlight yesterday. But, as you can see, I should have taken more.

I think it's already much better thinking about time compared to in-camera NR, but if we could take the darkframe automatically with a script, without having to put a "lens-cap" on would be even better.
Any ideas on how that is done by the camera, and how to do it with CHDK?
I can offer some help of an unexperienced student trying out all available languages :haha.
« Last Edit: 13 / April / 2008, 06:37:56 by jetzt »
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Re: (again)noise in long exposures or about almost "bulb mode"
« Reply #9 on: 13 / April / 2008, 06:59:24 »
For discussion: I think you need a new blackframe for every series:
I tried the above progress for my old 6JPEGs and the new after-series-bf.
Look at it yourself: (Sorry not so small.)


« Last Edit: 13 / April / 2008, 11:41:42 by jetzt »
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