Several previous posts on this subject do not get to the real issue.
Sorting by "date taken" is the most common sort sequence for most viewing programs. LR uses something of a relative change to a batch of selected pics from multiple sources that end up with wild unmeaningful dates. That works great to sync various camera's timing during a single shoot. But for scanned pics, or many other intermediate sources of pics (like Shutterfly) that date is changed to the "date captured" (date processed by that scanner or intermediate program). Example, to merge a number of pics from an event like a family birthday or wedding taken by multiple family members, I know the real date and want a way to force the date that I specify to change uniformily as I enter it across the entire batch. I may want to set the correct date first, then guess at the realtive time to make the sequence seem logical. (Walk down the aisle comes before the I do and kiss). Having pics from one good modern camera is a big aid as a master source, but for ancestor pics and others, all you have are scans of old prints.
Perhaps two selection buttons - "Relative Change"and "Specified Change."
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