ISO Override Settings are not right in EXIF data - General Discussion and Assistance - CHDK Forum

ISO Override Settings are not right in EXIF data

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ISO Override Settings are not right in EXIF data
« on: 19 / March / 2010, 05:27:38 »
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Hello, in both cameras, an G9 and a A590IS, the ISO Override Settings are not right in EXIF data.

Example: in A590, if overide settings are 4000 ISA, in the EXIF date of the shoted pic, is 6400 ISO.  Why??


in my G9, ISO override setings directly does not apply, and works the ones of the own camera.

Have anyone more seen that?

Rgds.

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Offline fe50

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Re: ISO Override Settings are not right in EXIF data
« Reply #1 on: 19 / March / 2010, 06:32:44 »
the ISO Override Settings are not right in EXIF data.
The meta data (EXIF) in the JPG images is written by the original Canon firmware routines.
There are two types of ISO values: the real ones & the Canon marketing ISO values, the marketing ones are significant higher.

The behaviour is camera dependent; normally the EXIF ISO value contains the nearest Canon marketing ISO value the original firmware knows.

Have a look to the EXIF maker notes (e.g. with EXIFTool) to see the "real" ISO values and also other available meta data.
Read also http://chdk.wikia.com/wiki/FAQ#Q._I.27ve_shot_some_RAW_pictures._How_do_I_process_them.3F for some more background informations...

BTW - such high ISO values doesn't make sense on P&S cameras; CHDK normally do not extend the cameras native ISO range much.

 

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