Suggest a script for zero noise technique - page 2 - Script Writing - CHDK Forum
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Suggest a script for zero noise technique

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Offline markanini

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Re: Suggest a script for zero noise technique
« Reply #10 on: 06 / December / 2015, 21:01:53 »
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After the initial shot it takes a underexposed shot, then an overexposed shot. I'd prefer and overexposed shot after the initial shot.
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Offline waterwingz

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Re: Suggest a script for zero noise technique
« Reply #11 on: 06 / December / 2015, 22:15:08 »
Quote from: markanini on 06 / December / 2015, 21:01:53
After the initial shot it takes a underexposed shot, then an overexposed shot. I'd prefer an overexposed shot after the initial shot.
Change
Code: [Select]
tv96val=tv-n*s/2
for i=1, n, 1 do
print("step=", i, "tv96=", tv96val)
fastshoot(av,sv,tv96val)
tv96val = tv96val+s
end
to
Code: [Select]
tv96val=tv+n*s/2
for i=1, n, 1 do
print("step=", i, "tv96=", tv96val)
fastshoot(av,sv,tv96val)
tv96val = tv96val-s
end
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Ported :   A1200    SD940   G10    Powershot N    G16
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Offline markanini

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Re: Suggest a script for zero noise technique
« Reply #12 on: 06 / December / 2015, 22:38:59 »
Hmm. With positive 'tV step size' the initial shot is underexposed and the second is normal. With negative 'tV step size' both are the same exposure. To clarify I want one normal exposure followed by one overexposed exposure.
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Offline waterwingz

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    • Waterwingz
Re: Suggest a script for zero noise technique
« Reply #13 on: 06 / December / 2015, 22:44:06 »
Quote from: markanini on 06 / December / 2015, 22:38:59
Hmm. With positive 'tV step size' the initial shot is underexposed and the second is normal. With negative 'tV step size' both are the same exposure. To clarify I want one normal exposure followed by one overexposed exposure.

Code: [Select]
fastshoot(av,sv,tv96val)
tv96val=tv+s
fastshoot(av,sv,tv96val)
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Ported :   A1200    SD940   G10    Powershot N    G16
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Offline ShahJahan

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Re: Suggest a script for zero noise technique
« Reply #14 on: 12 / January / 2016, 14:12:11 »
Quote from: markanini on 01 / December / 2015, 19:41:36
I want to bracket two exposures, One normal followed by one that is +4 f-stops by reducing the shutter speed. If possible with minimal delay between the two.

More about the zero noise technique: http://www.guillermoluijk.com/article/nonoise/index_en.htm

My camera is Canon s90.
You can do that without a script! In CHDK, find Auto Bracketing > Tv bracket > 4 Stops
Then set timer to 0 Sec, 3 Pics
This will shoot 3 pics in +4 0 -4
If you think 4 is too strong a stop, then you can set the timer to 0 Sec 5 Pics with 2 Stops and it will shoot +4 +2 0 -2 -4

Another way to remove noise (without HDR effect)
Use the interval.lua script (thanks waterwingz for showing me this script) and take 'n' number of Pics.
Then in photoshop, create a smart object and median stack all the images.

Technique learned from this place (it really works wonders, WITHOUT altering lighting conditions, like HDR does): http://petapixel.com/2013/05/29/a-look-at-reducing-noise-in-photographs-using-median-blending/
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The name ShahJahan comes from Persian, where Shah means King and Jahan means World,
so the name ShahJahan in its literal sense means King of the World.

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