@Jandro
It is probably a good idea to download the User Guide (see my signature)
The override section is at pages 8 .. 10
As you can see there, you will have to set both the "Override ISO Value" and the "Value Factor"
- Note that the camera will ignore ISO settings that it can not handle. Camera capabilities overview is
here:
http://chdk.wikia.com/wiki/CameraFeatures Unfortunately no data are available for
A470, but data for other camera's will give you an idea of what is possible
- AFAIK the Canon software will not show 'your' ISO in the EXIF data, to actually see the values CHDK applies, make them
show in the CHDK display:
go to Miscellaneous Values -> Show 'real' ISO or Show 'market' ISO (User guide page 30)
Hope that helps (a little)
wim