Problem with Field "Light Value"

[exifmaster]

Hi there,

I have a problem with reading out the field "Light Value". If I read out a JPG (Canon EOS5D) with full Exif data I get the value. If I used a manual attached lens without aperture-information I don't get the value back.

So f.e. If I'm taking a picture with a Canon 80-200L 2.8 the value "Light Value" is read out. If I use a manual attached lens without electronic contacts I get no value back (no entry at all). This may sound not unusual because someone may think this depends on the lens, but the behaviour is only on exiftool 8.x and 10.x, with the version 9.x I get the value back from both pictures. Regardless of the lens. And the value is even correct.

Any hints? Is there a 9.x version still available for linux? As workaround.

[Phil Harvey]

LightValue is a Composite tag which is calculated from Aperture, ShutterSpeed and ISO.  If any of those tags is not available then LightValue won't be calculated.

- Phil

[exifmaster]

Thanks for the answer phil. Is this value calculated from the cam or from the exiftool? In version 9.x it's in the exifinformation but not in 8.x or 10.x. It seems to be correct even without aperture in version 9.75.

Thomas

[Phil Harvey]

Hi Thomas,

The Composite tags are calculated by ExifTool.  There is another Light value tag that is stored by the camera, but I think this is only available in CRW files.  Use the -G1 option to see where the information is coming from.

- Phil