That/when

'the date when the photo was taken'

is that equivalent to...

'the date that the photo was taken' ?

I prefer the first but would like to use the second, though it does not sound right to me.

help!

I'd only use "the date/day when ..."

There's nothing wrong with it 

To me, both are correct:

The date when the photo was taken, and the date the photo was taken. You can omit the "when" there, as well as you can omit the "why" in: "the reason (why) I told you this is..."

To me, both are correct:

The date when the photo was taken, and the date the photo was taken. You can omit the "when" there, as well as you can omit the "why" in: "the reason (why) I told you this is..."

To me again, the only alternative would be "the date on which the..." and "the reason for which I ..."

This doesn't mean other versions can't be heard and perfectly understood.