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I found ExifTool, which allows you to edit almost any piece of metadata from the command line.

However if you try to edit the shutter speed (using exiftool file.tif -shutterspeed=1/200), it simply says:

Warning: Sorry, shutterspeed is not writable

Is there any way (using any tool) to change the exposure time in the metadata? Either in a CR2 or TIFF file.

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    \$\begingroup\$ Why would you want to? It's probably not supported as a writable field because in general no one wants to write it. \$\endgroup\$
    – Chris H
    Apr 3, 2016 at 12:53
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    \$\begingroup\$ I'm merging bracketed exposures using picturenaut, which only takes shutter speed and aperture into account, not ISO. Often I bracket with ISO as well to avoid super long exposures, so I'd like to edit the exposure times as if all the brackets were shot with ISO 100. Make sense? \$\endgroup\$
    – Greg Zaal
    Apr 3, 2016 at 14:01
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    \$\begingroup\$ That does make sense. I'd say the solution is to use better software. As I'm mainly on Linux and use GIMP even on Windows, I use a plugin for that for HDR. It doesn't rely on the exposure details (which is just as well as I use its flexibility for related tasks where the illumination changes significantly) \$\endgroup\$
    – Chris H
    Apr 3, 2016 at 14:27
  • \$\begingroup\$ @ChrisH: Another situation where this is necessary is when using a manual lens without electronic contacts. The camera cannot guess the aperture. \$\endgroup\$ Dec 7, 2017 at 22:47
  • \$\begingroup\$ @Luis I have no idea whether the aperture field is writable. That would make more sense. \$\endgroup\$
    – Chris H
    Dec 8, 2017 at 7:00

2 Answers 2

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Using ExifTool, ShutterSpeed is not an actual tag within the file, it's a tag derived from several other values (See Extra Tags). That's why it's grouped under Composite Tags when you follow ExifTool FAQ 3.

As you discovered, the actual tag you want to write to is EXIF:ExposureTime using ExifTool.

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I found another tool which seems to work just fine: Exiv2

exiv2 -M"set Exif.Photo.ExposureTime 1/200" file.tif
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    \$\begingroup\$ Note that you changed more than just the tool. You switched from the read-only field to the writeable field. So it seems a bit unfair to blame the tool! \$\endgroup\$ Apr 3, 2016 at 18:33
  • \$\begingroup\$ Actually, this does not work for Aperture either. \$\endgroup\$ Dec 7, 2017 at 22:47

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