«

Floyd L. Davidson wrote:
[]
> That's a valid point, but considering reality, the UTC
> suggestion is almost certainly the _only_ solution
> likely to provide you with accurate results in the end.
> It hasn't much to do with the cameras or the "best case"
> situation, it has to do with human nature...

I start to wonder about my answers when Floyd agrees with me!

<G>

David

On Thu, 01 Nov 2007 01:23:08 -0900, (Floyd L.
Davidson) wrote:

>That's a valid point, but considering reality, the UTC
>suggestion is almost certainly the _only_ solution
>likely to provide you with accurate results in the end.
>It hasn't much to do with the cameras or the "best case"
>situation, it has to do with human nature...

Thanks - valid points, to be sure.

However, there are some factors here that come into play in my favor:

1. I'm on a PC a LOT. And it's (for me) easier to set the clock
correctly on the laptop than on 3 different cameras.

2. I'm thinking seriously about using UTC time. I can certainly see
the advantages. But I also like being able to look at a photo and
knowing that it was taken at such-and-such a local time.

3. Even if I forgot to change the time zone on the laptop, at least
if all 3 cameras we use are synched the same, it's easy for me to use
a utility to adjust the exif data by an hour. What drove me nuts was
interlaying all the pictures together when we went through the Panama
Canal (for one instance), and having one camera about 3.5 minutes off
the other. I finally found some pictures showing a clock in them and
was able to put in a pretty good offset to adjust one camera to match
the other.

When I go on a trip, I get the camera maintenance duties. The routine
is normally that at the end of the day, I pull the batteries and
recharge them, download all the cards to the laptop (Downloader Pro),
copy the downloaded images to a backup USB drive, and clean lenses.
If I have filled cards and know there is a big shooting day coming up,
I reformat cards in-camera (never until I have two copies, and
sometimes a backup on DVD). The problem here is that this is an
end-of-day routine, at which point it is too late to change the camera
time if we changed into a different time zone that day. Still, if the
cameras at least match, it is a lot better than when they don't.

Craig Johnson wrote:
> 3. Even if I forgot to change the time zone on the laptop, at least
> if all 3 cameras we use are synched the same, it's easy for me to use
> a utility to adjust the exif data by an hour. What drove me nuts was
> interlaying all the pictures together when we went through the Panama
> Canal (for one instance), and having one camera about 3.5 minutes off
> the other. I finally found some pictures showing a clock in them and
> was able to put in a pretty good offset to adjust one camera to match
> the other.


Hi, Craig.

I don't think there is a utility for this - if you find it, let me know.
I use an alternative that isn't as easy as plugging the camera into
the PC, but it works very well, and after-the-fact too... we do it all
the time to sync multiple cameras down to the second. It's far more
accurate than you can set through the menus.

Just take both cameras and click the shutter on both simultaneously. If
you want highly accurate time (not just sync'd time), point the camera
at a highly accurate clock when you do this. This gives you a reference
photo for how much the cameras need to be adjusted.

When you download the images, put their files in separate directories.
Using a tool like ExifTool, read the timestamps on the 2 reference
photos, calc their offset and figure out how much to adjust each camera.
(ExifTool is an open source set of Perl scripts.)

To read out the timestamps with ExifTool:
perl exiftool -DateTimeOriginal MyPhoto.nef

This adds exactly 3 minutes to every image in the current folder:
perl exiftool -overwrite_original -AllDates+=00:03:00 .

And this syncs the filesystem date with the EXIF timestamp
perl exiftool "-DateTimeOriginal>FileModifyDate" .

With this, neither camera needs to keep the right time, and you can
adjust to any timezone you wish, without having to remember to do it
ahead of time.

Cheers,
Richard

Richard H. wrote:

> Hi, Craig.
>
> I don't think there is a utility for this - if you find it, let me know.
> I use an alternative that isn't as easy as plugging the camera into the
> PC, but it works very well, and after-the-fact too... we do it all the
> time to sync multiple cameras down to the second. It's far more
> accurate than you can set through the menus.
>
> Just take both cameras and click the shutter on both simultaneously. If
> you want highly accurate time (not just sync'd time), point the camera
> at a highly accurate clock when you do this. This gives you a reference
> photo for how much the cameras need to be adjusted.
>
> When you download the images, put their files in separate directories.
> Using a tool like ExifTool, read the timestamps on the 2 reference
> photos, calc their offset and figure out how much to adjust each camera.
> (ExifTool is an open source set of Perl scripts.)
>
> To read out the timestamps with ExifTool:
> perl exiftool -DateTimeOriginal MyPhoto.nef
>
> This adds exactly 3 minutes to every image in the current folder:
> perl exiftool -overwrite_original -AllDates+=00:03:00 .
>
> And this syncs the filesystem date with the EXIF timestamp
> perl exiftool "-DateTimeOriginal>FileModifyDate" .
>
> With this, neither camera needs to keep the right time, and you can
> adjust to any timezone you wish, without having to remember to do it
> ahead of time.
>
> Cheers,
> Richard


Nice! That's clever.

->HS