I'm hoping that both Mixture and Captain Bloggs will chip in here!
You rang, Sir ?
Aaah... so, if I get to the nutshell, your question is about de-duplication of your infinitesimal collection of fine photographs ?
If that is the case. The technical answer to your question is that you want to hash the files and trash duplicate hashes.
Hashing being a term for cryptographic magic that will take a file, any file... and produce a string, e.g. "a92701812cff2cf954b22a1adb5c38f166ba409e" ..... that string is
guaranteed to be unique for the data in that file ... thus if you had two files with the same hash, you would have exact duplicate files, that is a
guaranteed fact because its the very reason hashes were invented. There is a little issue of "hash collisions" but as long as you choose the correct hash algorithm in the first place, the guarantee of being able to identify duplicate files still holds.
Because its cryptography, and thus mathematics, modern computers are able to handle mathematics with aplomb.... thus even if you feed a massive file into a hash algorithm, the computer will typically spit out a result in a matter of seconds.
But I digress.....
Assuming you are not familiar with the dark arts of scripting, what platform do you find your self on ? Linux, Mac, Windows ? I shall then have a sniff around the internet and see if I can mention a few bits of software that may guide you on your quest....
Whilst you could do this in Lightroom (or another photo manager), it would not be an effective use of computing resources because importing stuff to Lightroom (or another photo manager) involves multiple things behind the scenes. If you've got a large volume to deal with, you really want something that does hashes and nothing else.
Moving swiftly on to your extra questions.....
> will Lightroom run a slideshow built from several tags? I expect so but thought I should ask.
To be honest, slideshows is one of the features I use least in Lightroom (just because I've little need for it, not that I've any problems with the way Lightroom does slideshows).
I have fired up my copy of Lightroom, it looks like what you'll do is create a Smart Collection and run a slideshow on that. You'll probably be making a lot of use of Smart Collections anyway, because its a seriously awesome feature, which will mean the answer to your question will effectively be yes, since you're likely to already have the Smart Collection in place that you want to run a slideshow on.
> Can I use Lightwave to integrate stills and video? Video is generally family stuff in clips of only a few minutes (once edited). I realise that I'll have to 'chop up' the 30 or 45 minute contents of each tape, but that's fine.
Lightwave (?) or Lightroom ?
I
think Lightroom has some form of video support. But whether this goes further than just cataloguing I don't know.
I don't do a huge amount of video, and what video I do do, I use Adobe Prelude and Premiere.
But by the looks of things (
http://tv.adobe.com/watch/getting-st...h-dslr-video-/), it looks like Lightroom has had video support since version 4.