If you’re using your GPS and one of the applications that geotags photos based on a GPS track log you’ll have realised that it’s crucial to have the camera’s clock set correctly - otherwise the image locations will be shifted. If you’re lucky the software you’re using will allow you to specify the time difference between the camera’s clock and real (GPS) time. Here’s a tip for working out exactly what the camera’s time error is.
Find an accurate clock - the one in your GPS is good - or use your computer clock if it’s set to internet time. Now set the clock to display hours, minutes and seconds and take a picture of it with the camera. You’ll end up with something like this:
So now you have the time the camera thinks it was (in the image metadata) and the time the rest of the world thinks it was (in the picture). Subtract camera time from real time and feed the result into your geotagging software. In this case the camera thought it was 22:19:46 and the real world thought it was 23:19:27 so the error is 1 hour minus 19 seconds - or 3581 seconds.