When I found this subject, the direct sunlight shining through the trees at my left, onto the water, was too extensive, so I had to come back the following day, at least half an hour earlier. I just made it and luckily everything else was the same. Morning sun was on the trees which are reflected in the brook. I focussed a little below the surface of the water and close to the sharpest plane for the disturbed reflections (much nearer than would be optimum for smooth reflections). The shutter speed was long enough to allow just the correct degree of movement, either 1/8th or 1/15th of a second, I have forgotten which, and the aperture of the 8 1/4-inch lens was uncomfortably large (between f/8 and f/11). I had to wait for leaves to stop floating by, since they would have been both objectionably blurred and very distracting. I made several exposures, all the same, but only one is just right. The others have a little too much movement in the lower right, which blurs away the bright red there. A couple of days later, I came back with faster film, which I had thought might help. The scene was completely changed. The brook had dropped two or three inches, so the rocks immediately upstream, which had just been breaking the surface, thereby creating the right degree and sort of rippling movement, were now protruding too far and the ripples were almost gone. The next time I came back for a look, it had rained and the water was a few inches too high, submerging the rocks entirely, and was again devoid of the critical surface texture, without which the light didn't get so beautifully intermingled.