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Reading ISO and the maximum exposure duration

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Reading ISO and the maximum exposure duration
« on: 04 / November / 2022, 14:10:47 »
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Does anyone know how to extend the maximum auto-exposure duration in P mode past one second? (In Tv mode, the camera can record for 15 seconds; in P mode, it cannot.) Is it possible to extract the ISO setting the camera used from the JPG file as well? It appears the blanks in the EXIF data, yet Picasa displays a "user comment" that is 264 bytes long, suggesting that it may be present. I am using an A640.

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Offline philmoz

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Re: Reading ISO and the maximum exposure duration
« Reply #1 on: 04 / November / 2022, 17:30:47 »
Does anyone know how to extend the maximum auto-exposure duration in P mode past one second? (In Tv mode, the camera can record for 15 seconds; in P mode, it cannot.)


You can do this using CHDK overrides.


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Is it possible to extract the ISO setting the camera used from the JPG file as well? It appears the blanks in the EXIF data, yet Picasa displays a "user comment" that is 264 bytes long, suggesting that it may be present. I am using an A640.


This is probably a problem with Picasa. I looked at a sample A640 JPEG image and all the exposure settings are visible in the EXIF data.

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Offline reyalp

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Re: Reading ISO and the maximum exposure duration
« Reply #2 on: 04 / November / 2022, 18:35:10 »
Does anyone know how to extend the maximum auto-exposure duration in P mode past one second? (In Tv mode, the camera can record for 15 seconds; in P mode, it cannot.)
You can do this using CHDK overrides.
To add to this a bit, you can use CHDK to override the exposure in P, but you cannot tell the Canon firmware to do auto-exposure beyond 1s in P. So using CHDK override in P wouldn't be much different from using Tv, since you still have to pick a specific shutter value.

You could write a script to do your own auto-exposure with Tv beyond 1s.
Don't forget what the H stands for.

 

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