Okay. So you're shooting ruins in the Greek Islands with your bulletproof old Linhof Technika, when the triple extension English Leather bellows starts doing its legendary Dance of the Seven Veils, with too many holes and creases to possibly tape over.

You're in Paris taking a tour to Geverny tomorrow before flying home the following day, when your Haliburton Case with two Nikon F5's and all their lenses disappears from your hotel room. Fortunately, your three weeks of exposed Velvia are in untouched ziplocks.

Or you're in Gatlinburg in October, driving to Cade's Cove for the magnificant Autumn leaves, when your 12 MP Canon D5 (which arrived from B&H as you were packing to leave home, and you've already made hundreds of pictures with it driving down the Blue Ridge ), refuses to turn on. Bad battery? Bad camera? Idiot photographer? When you get back to the hotel you'll find that somehow you accidentally unplugged the charger overnight. But that's no help NOW.

My question: what do you take for backup? And what are the criteria for selecting it?