- even using filename sorting is no good to me as I often shoot with two bodies.
You could always filter by the Camera Serial Number and work on the photos for that particular camera sorted by filename.
I'm not able to reproduce this -- with my raw files from a couple different cameras, LR 5.7 is retaining the fractional seconds in XMP:DateTimeOriginal as well as in the internal catalog capture time (as reported by the LR plugin SDK).
Perhaps you can upload a sample raw file along with its .xmp to Dropbox (or similar) and we can take a more detailed look, to see what might be going on?
Thanks for this; whilst preparing data for the Dropbox, I have realised that it is not quite as bad as I thought! The photos which show the problem are only from one of my cameras. Yesterday I realised after loading the pictures into LR that I had not adjusted the clock on one camera for the end of daylight saving in Europe at the end of October, so I selected all photos from that camera and adjusted their Capture time by 59 minutes to bring them into line with the other camera; I suspect that it is at this stage that the fractions of a second are lost as there is no place for fractions of a second on that menu. I think that this section of the xmp file sows that transaction:
aux:LensInfo="700/10 2000/10 28/10 28/10"
aux:Lens="70.0-200.0 mm f/2.8"
I find it interesting exif does not seem to have the fraction, whereas xmp does, but photoshop:DateCreated seems to be the one used in sorting and has lost the .82
Given this further information, I presume that a RAW file and xmp may no longer be appropriate? it is easily reproduced by taking a copy of an existing xmp and then adjusting the Creation time of the image and comparing the "before" and "after" xmp. The photoshop:DateCreated record will have lost its fractions of a second which I believe is a bug.
Thanks for pointing me in the right direction to some extent; having adjusted my cameras to be in sync, at least I know this is a problem which can only upset me twice a year!
I'm afraid that won't work as I need to combine shots from 2 (or sometimes more), cameras to make a chronological sequence of shots which tell the story of a game. See my response to John R. Ellis for further information.
Thanks for your interest
I've submitted a bug report: Lightroom: Edit Capture Time doesn't preserve fractional seconds. Please visit that topic and add your vote.
If you encounter this problem again, you could use the free Exiftool to adjust the date/time outside of LR.