I guess when you use large difficult cameras, have a very limited number of exposures available, changing elements, lengthy developing and printing and miles of walking to get to the spot and come back, you need to have everything there when you click the shutter!
aristotelis grammatikakis www.arigram.gr Real photographs, created in camera, 100% organic,
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Since Ansel spent most of his time in California, I imagine that is where he came up with it. That is where his darkroom was and I do believe that someone who is faced with developing and printing his own images, that he himself took is more likely to have such a conception. On the whole idea of the Zone System one should remember that he had a colleague in this effort: Fred Archer. My recollection is that Fred and Ansel taught together and their desire and need to communicate with students probably had much to do with the clarifying the conception and practical aspects of Zone System techniques.
As a side note I find the term previsualize to be very curious. It is almost like saying visualizing prior to visualizing. It make me wonder if Yoge Berra helped coin this term.
The way I understand it the idea came when he shot the moon over half dome. His last plate, a long as hell day and he knew what he shot of that scene was not going to be what he wanted. That was when, as he saw it, how the final print would look and what it would take to get it there. That is his story, anyway.
Technological society has succeeded in multiplying the opportunities for pleasure, but it has great difficulty in generating joy. Pope Paul VI
So, I think the "greats" were true to their visions, once their visions no longer sucked. Ralph Barker 12/2004