Quote Originally Posted by Donald Miller
The first time that I remember Adams mentioning this was in regard to making his exposure on... Monolith The Face of Halfdome...As I recall he made two exposures that afternoon and then he had a vision of what he wanted the image to be and exposed his last glass plate with the red filter. I believe that exposure was made in 1927.

Since this vision occurred prior to making his pivotal exposure, I would assume that this would mean previsualization.
From Adams, Ansel; Examples The Making of 40 Photographs, p. 4:

"This photograph represents my first conscious visualization, in my mind's eye. I saw (with reasonable completeness) the final image as made with the red filter. I knew little of 'controls'. My exposures were based on experience, and I followed the usual basic information on lenses, filter factors, and development times. The red filter did what I expected it to do. I was fortunate that I had that twelfth plate left!

Over the years I became increasingly aware of the importance of visualization. The ability to anticipate - to see in the mind's eye, so to speak - the final print while viewing the subject makes it possible to apply the numerous controls of the craft in precise ways that contribute to achieving the desired results."

......

Ibid, p. 5:

"I can still recall the excitement of seeing the visualization "come true" when I removed the plate from the fixing bath for examination. The desired values were all there in their beautiful negative interpretation. This was one of the most exciting moments of my photographic career."