Windows "date modified" and daylight savings time
in [Digital Cameras]
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From: Ofnuts on 3 Nov 2009 17:40 Eric Stevens wrote: > On Tue, 3 Nov 2009 20:57:14 +0000 (UTC), Toxic <staring(a)my_hd.tv> > wrote: > >> On Tue, 03 Nov 2009 13:56:43 +0000, David J Taylor wrote: >> >>> I keep my camera set to UTC rather than local time >> >> Good idea, >> and since I've got to go in and dither its clock one of these days, >> I think I'll do likewise. > > My camera (Nikon D300) is set to synchronise time with my computer > every time I connect the two. The computer (Windows XP) shows local > time, including the adjustment for DST. It also is synchronised daily > with a time signal from somewhere (USN Hawaii?) All of this is very > convenient and much more meaningful than me having to maintain my > camera at UTC. It's also a lot easier if you geotag your photos using a GPS log file. -- Bertrand
From: J�rgen Exner on 4 Nov 2009 01:52 bucky3 <bucky3(a)mail.com> wrote: >Just curious, how do other operating systems (like Unix, Mac) handle >the file timestamp in regards to DST? It's not an issue because all times/dates are stored in UTC (or actually seconds since the epoch) and converted to local time for display purposes only. >Do they have the same problem, >or do they handle it better? Not sure how you define "problem" and "better". The exact time is available, it is up to you as a user to decide how you want to display it. I think your problem is not a problem at all. Or maybe it's a problem where there is no meaningful solution. Or maybe you didn't think it through all the way. DST is only one very small factor in dealing with local time. Example: If photos have been taken in Sydney at lunch time and now you are looking at those files back home in NewYork, what time stamp would you expect: 13:00 (the local time at the place those files were created) or 22:00 the previous day (the local time of when the files were created at the place you are looking at the files now)? Now imagine that you uploaded those files minutes after you took them to your home server in NY, and another family member uploaded some other photos locally in NY 2 hours later. What time sequence would you like to see: your photos first or his photos first? Because by local time based on where the photos were taken his would be first by 13 hours although they were taken 2 hours after yours. So no, there is no golden bullet and the only sensible option is indeed using UTC and thus having an absolut target, that is not moving with crossing each time zone boundary and not moving with every switch between DST and non-DST, either. jue
From: David J Taylor on 4 Nov 2009 01:55 "Eric Stevens" <> wrote in message news:5s71f5p6ertaenre4l8uk09cetnbhhbc50(a)4ax.com... [] > My camera (Nikon D300) is set to synchronise time with my computer > every time I connect the two. The computer (Windows XP) shows local > time, including the adjustment for DST. It also is synchronised daily > with a time signal from somewhere (USN Hawaii?) All of this is very > convenient and much more meaningful than me having to maintain my > camera at UTC. > > Eric Stevens If you want better than a daily sync, look at NTP: http://www.meinberg.de/english/sw/ntp.htm You can keep your PC within a fraction of a second using an Internet connection. Cheers, David
From: David J Taylor on 4 Nov 2009 02:16 "Ofnuts" <> wrote in message news:4af044f8$0$30818$426a74cc(a)news.free.fr... > David J Taylor wrote: >> >> "Ofnuts" <> wrote in message >> news:4af004ab$0$25364$426a74cc(a)news.free.fr... >> [] >>> A timestamp is absolute. In computers it is stored as the number of >>> seconds (or milliseconds, or nanoseconds) since a reference time >>> (00:00 UTC on January 1st, 1970 for Unix and a lot of web-related >>> things)(*). >> >> .. conveniently forgetting about things like leap seconds, perhaps? > > No, they are taken in account (assuming the display and parsing code are > correct (mostly the display, since most serious computers > self-synchronize via NTP). Unix time ignores leap seconds, at least according to: http://en.wikipedia.org/wiki/Unix_time and that's my experience as well. The "number of seconds" does /not/ include the leap seconds. To test, try seeing whether the Unix time tor the start of a day is exactly divisible by 86400 - e.g. 1257292800 (4-Nov-2009 at 00:00:00). If Unix time included the leap-second count, the start of a day should be n * 86400 + 24. (IIRC). [] > Not even sure of the date part. If a file is stamped at 00:30 on June > 21st, will Window show it later as stamped at 23:30 on June 21st or at > 23:30 on June 20th? > > -- > Bertrand An interesting point, although to some extent one I face all the time as, for example, most of my "daytime" photographs taken in Australia cover two UTC calendar days. As my camera and hence my EXIF information stays on UTC, the photos have a continually increasing sequence number when renamed, even over a winter/summer time change. My photos have a name - typically: 2009-09-24-0826-57.jpg Cheers, David
From: J. Clarke on 4 Nov 2009 07:02
David J Taylor wrote: > "Eric Stevens" <> wrote in message > news:5s71f5p6ertaenre4l8uk09cetnbhhbc50(a)4ax.com... > [] >> My camera (Nikon D300) is set to synchronise time with my computer >> every time I connect the two. The computer (Windows XP) shows local >> time, including the adjustment for DST. It also is synchronised daily >> with a time signal from somewhere (USN Hawaii?) All of this is very >> convenient and much more meaningful than me having to maintain my >> camera at UTC. >> >> Eric Stevens > > If you want better than a daily sync, look at NTP: > > http://www.meinberg.de/english/sw/ntp.htm > > You can keep your PC within a fraction of a second using an Internet > connection. You don't need "NTP for Windows" with Windows you know. The Windows Time Service is quite capable of synchronizing to an NTP server, and in fact Vista does that out of the box unless it's on a domain, in which case it synchronizes to the domain controller. On XP and earlier you have to do some digging to set it up, on Vista it's set up right off the clock application in the system tray on the lower right. For XP the procedure can be found at http://support.microsoft.com/kb/314054#EXTERNAL. There's a link from there to the procedure for Windows 2000. |