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Reading ISO and the maximum exposure duration

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Offline SandraEllis

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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 »
Quote from: SandraEllis on 04 / November / 2022, 14:10:47
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.


Quote
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 »
Quote from: philmoz on 04 / November / 2022, 17:30:47
Quote from: SandraEllis on 04 / November / 2022, 14:10:47
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.
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.
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