HDR script for A610: EV value in Exif tags (solved) - Script Writing - CHDK Forum
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HDR script for A610: EV value in Exif tags (solved)

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Offline qvex

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HDR script for A610: EV value in Exif tags (solved)
« on: 30 / March / 2010, 18:18:47 »
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When i manually set the EV with my A610, the exif tag "exposure bias value" in the resulting photos contains the correct value (e.g. -2, -1, 0, 1, and 2 when shooting 5 photos).
But when i use the HDR script
http://chdk.wikia.com/wiki/UBASIC/Scripts:_an_ultra_fast_HDR_bracketing_script_for_A6xx,
all pictures have the "exposure bias value" set to 0 in their exif tags, although there is a set_prop 25 and 26 in the loop and the pics are of different brightness like expected. What could be the reason?

P.S.
It's not really important, i can set the EV manually in Photomatix (which bothered me about missing EV Exif tags),  but that is more work.



 
« Last Edit: 04 / April / 2010, 18:55:51 by qvex »
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Offline fe50

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Re: HDR script for A610: EV value in Exif tags
« Reply #1 on: 31 / March / 2010, 01:15:00 »
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Offline PS

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Re: HDR script for A610: EV value in Exif tags
« Reply #2 on: 31 / March / 2010, 14:36:55 »
I thought that "exposure bias value" expresses the difference between your settings and camera's metering.
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Offline qvex

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Re: HDR script for A610: EV value in Exif tags
« Reply #3 on: 31 / March / 2010, 17:42:38 »
Thanks for your welcome and answer.
Sorry, i have posted my question before reading the requirements for the script  thoroughly, especially that i have to use Fingalo's special build because of the set_prop directive, which is the directive that seems to produce random/false results on my allbest build. I will try it with that build.
Edit: again written too fast. Fingalo says, all his features are already in allbest build.

Yesterday i got all "Exposure bias Values" as 0, today, without changing any parameters, i got -4, -3, -2, -1, 0. The out of range -4 is not shown on the display of the camera, but by irfanview, exiftool shows "+1023" instead of -4. The other values (-3,-2,-1,0) where displayed correctly by camera, irfanview and exiftool.

@PS: i think that "Exposure bias value" shown by Irfanview is the same as EV, because if i set EV manually (-2,-1,0,1,2), the correct values appear in this tag. Also Photomatix does'nt complain about missing EV tags, if this tag is set differently in all 5 pics, but only yesterday when all 5 pics were tagged with 0.
As far as i understand, the "exposure bias value" shown by irfanview corresponds to the "exposure compensation" value shown by exiftool, as they always contain the same values.
So my problem is not, as i thought yesterday, that the script doesn't write EV tags, but seems to write wrong EV values (my build is allbest 0.9.8-825 for FW100e)
When i have time I will have a deeper look at it, if i figure it out, i will post it.
Thanks again.
« Last Edit: 31 / March / 2010, 19:26:32 by qvex »
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Offline qvex

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Re: HDR script for A610: EV value in Exif tags (solved)
« Reply #4 on: 04 / April / 2010, 16:43:01 »
The script calculates the EV compensation in relation to the EV which is set in the normal camera menu. If no compensation is set (EV=0) and 5 pictures are shot, the resulting values are -2,-1,0,1,2 as described in the wikia. But if  EV is already set for example to -2 , the resulting EV are -4,-3,-2,-1,0.
« Last Edit: 04 / April / 2010, 22:40:00 by qvex »
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Offline vibes35

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Re: HDR script for A610: EV value in Exif tags (solved)
« Reply #5 on: 16 / April / 2010, 16:05:36 »
Great script! I tried this with my Canon SX10 Powershot- it said started P, TV, AV and then ended.

It did not take any pictures?! Am I missing something or maybe this script will not work with my camera?

Thanks!  :)
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