New answers tagged iso
F/22 suggests to me that the photographer first took some pictures with nearby objects in the foreground and then forgot (or didn't bother) to increase the aperture for this particular shot. The ISO setting of 640 is then quite appropriate, you can go lower with a longer exposue time, but as the other answerers point out that can cause problems if the clouds ...
1) Be simple. (s)he forgot to switch to the lower ISO. ). For example, (s)he wanted to catch a bird before. 2) But I heard one story from an older photographer (?) about the long exposure (sensor reheating during the long exposure): sometimes it's better using short high ISO shot vs. long exposure shot to avoid noise. The best solution to make two shorts ...
A very narrow aperture such as f22, which allows for an almost infinite Depth of Field, lets in very little light. ISO 640 may have been required to ensure the shutter speed stayed at a reasonable level, if the photographer didn't want to risk camera shake from wind or cloud blur.
Perhaps the photographer believes that ISO 640 can be LESS noisy than ISO 100. I'm not necessarily supporting that viewpoint, just stating that there is one.
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