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Max exposure time and reading ISO

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Offline Dave92F1

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Max exposure time and reading ISO
« on: 17 / January / 2021, 15:50:26 »
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Anybody know if there's a way to increase the maximum auto-exposure time in P mode from 1 second? (The camera will do 15 seconds in Tv mode, but not in P mode).

Also, is there a way to read the ISO chosen by the camera from the JPG file? It seems this field isn't filled out in the EXIF data (altho Picasa shows a "user comment" of 264 bytes - maybe it's in there. Anybody know how to decode the user comment?)

I'm using an A640.
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Offline reyalp

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Re: Max exposure time and reading ISO
« Reply #1 on: 17 / January / 2021, 17:37:26 »
Quote from: Dave92F1 on 17 / January / 2021, 15:50:26
Anybody know if there's a way to increase the maximum auto-exposure time in P mode from 1 second? (The camera will do 15 seconds in Tv mode, but not in P mode).
There is not. You can calculate the exposure yourself in script using the camera measured Bv value and the APEX equation

Quote
Also, is there a way to read the ISO chosen by the camera from the JPG file? It seems this field isn't filled out in the EXIF data (altho Picasa shows a "user comment" of 264 bytes - maybe it's in there. Anybody know how to decode the user comment?)
ISO should be recorded in the EXIF, in standard ISO tag and possibly in some of the "maker note" tags. It is not recorded in the user comment. See https://exiftool.org/TagNames/EXIF.html

edit:
Mea culpa, I was wrong about the standard ISO tag. exiftool shows an ISO value, but it's actually a composite value based on makernote tags, as described in this response: https://chdk.setepontos.com/index.php?topic=14218.msg145022#msg145022
« Last Edit: 23 / January / 2021, 00:11:48 by reyalp »
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