Most USA users -- set your camera clocks ahead

Started 4 months ago | Discussions thread
GeorgianBay1939
GeorgianBay1939 Veteran Member • Posts: 4,044
A Modest Proposal ...
3

… is that we should all do away with time zones and the related daylight/standard seasonal switching.

We should all just use UTC (or GMT or Zulu) any place, any season.

As a Canadian I was brought up believing that Sir Sanford Fleming “invented” the system of the 24 standard time zones around Earth. I have since learned that many folks, (including Quirico Filopanti / Giuseppe Barilli in 1858), have proposed universal time with zones earlier than Fleming’s 1884 advocacy of 24 zones centred on a Prime Meridian through Greenwich, England.

The 24 time zones are typically 1 hour apart, 15º of “apparent” travel of Sun, or equivalently, the angular separations of overhead Solar Noons from hour to hour as Earth rotates on its axis, ——— the zones being centred on the Prime Meridian passing through Greenwich England . (Yes, we know about the more complicated IRM .)

But as seen below, the 15º “hour” is modified by human political boundaries leading to an ever changing world time zone map:

Recent version of world time zone map

The boundaries may be national boundaries or state/canton/provincial/territorial boundaries, with some being even modified by municipal boundaries.

There’s also a variety of local changes including the Newfoundland Time Zone , and a patchwork of Daylight Saving Times particularly at high latitudes where sunrise/set times vary a lot between summer and winter seasons. And there is Saskatchewan .

So we end up with a medley of geographical, political and seasonal times to keep track of on our watches, cameras and other devices that are not connected to some sort of time server.

I spent a good part of my life using GMT or UTC all of the time. My “time of day” was not related to sun position, but to UTC. That is the time system that I used for flight planning, reading weather maps, target timing, and organizing my day. It didn’t change from location to location and didn’t change with the time of year. I carried one universal time on my wrist. I still do in my cameras and in my car. I don’t know how to disable the changing times in my iPhone.

It is easy for me to know that my current time is about 2018-03-12T14:30Z or the year 2018, month 03, day 12, 14th hour, 30 minutes UTC (Zulu). Which works out to a local sun time of about 10:30 AM EDT on Georgian Bay (Longitude ~81ºW, about 6º later than the nominal centre (75ºW) of the (-5 hr) Eastern Time Zone. The 75º angular separation between EST and UTC gives a time delay of (75º/15º) of 5 hours between when the sun is overhead Greenwich and overhead Georgian Bay, ON. (EDT gives a 4 hour difference.)

It takes the apparent Sun to move 360º in 24 hrs or 15º in 1 hr or 60 minutes. So the apparent sun is overhead about (6º/15º) X 60m or 24 minutes later than overhead Longitude 75º. If the Earth’s orbit were circular and if its axis of rotation were perpendicular to its orbital plan, that would be enough to calibrate my watch to give local sun time vs UTC. But since Earth’s orbit is elliptical , with a spin axis tilted at about 23.43693º (and slowly decreasing) we need to also use the EOT to get the relationship between clock time (UTC) and local solar time .

So why do we insist on using a local sun time that was useful to non-travelling folks up to the late 1800s? Sundials make nice sculptures at Science Centres but they are no longer useful to keep time!

Why not accept the fact that we’ve come a long way, able to circle Earth in 90 minutes? (To keep their clocks synched with ground clocks astronauts would have to change their watches every 3.75 minutes. Kinda dumb, eh?)

Why not everyone use UTC, accepting the fact that the Prime Meridian goes through Greenwich England?

I’m sure that the Brits would appreciate the fact that their standard time is “right”.

That way I wouldn’t have to bother resetting my disconnected clocks, including those in my cameras. Maybe that is why I set my camera clocks to UTC and leave them that way. I just make sure that they’re reasonably synchronized from time to time, while other folks are springing forward, falling back and keeping track of zone boundaries when travelling easterly or westerly.

Of course such a change would require folks to sit around a table to make it possible. And a lot of people would have to learn how time is constructed. But it that such a bad thing? Or are we destined to be forever trapped in our cultural upbringing?

I believe in a wider application of Kelly Johnson's KISS Principle .

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Tom
The best part of growing old is having the opportunity to do so.
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