Hi.
I don't know about enlightening you, but I think I can explain what's going on.
But first, I've never seen or used "Auto CHDK to EXIF tool" but I can guess what it does...
(is that thing even around anymore, the link on the Software wiki page leads to a 404 at zshare, and wasn't this Barney's, and de-sticky'd a while ago??) Yes, the former is probably the correct one, and the reason it's not exactly 1/8000th is the maker notes values are calculated via the
APEX system and not from a look-up table. IIRC the field for Maker Note #22 is the shutter speed you
set, regardless if the camera you have can shoot at that speed or not. That's part of the problem, you have to know the limitations of your model; just because it
says it shot at ISO 10 and records this in the tag, doesn't make it so.
That program is probably a front-end to
exiftool, I'm sorry I don't know it, maybe someone else can help, I'll just pretend you're using exiftool directly. You can have duplicate tag names, as well as tag numbers, I don't know how to do it with "Auto CHDK to EXIF tool" but you'd add
-D (decimal) or
-H (hexidecimal) to your exiftool command line so you can differentiate tags... something like:
exiftool -D -G -a some_image.jpg/crw/dng. You'll notice that the one you want is the highest number, #22 vs. the other Canon:ExposureTime values (#6 I think), so this will be read as 'the' value when you query that tag.
So to change the EXIF:ExposureTime to match the Canon maker note, just do:
exiftool '-canon:exposuretime>exif:exposuretime' some_image.jpg/crw/dng (note the quoting, and experiment on images you don't care if you lose the tag info.) This will result in the new exif & composite values being 1/8192th as you'd expect; check it with:
exiftool -shutterspeed some_image.jpg/crw/dng.
re: the comment problem; that's something that this "Auto CHDK to EXIF tool" thing is doing, normally the comment is blank straight out of the camera... to blank the comment field for all images in a directory with exiftool, do (in that directory):
exiftool -comment= *.jpg/crw/dngHave fun, and hope this helps...
