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<blockquote data-quote="nickt" data-source="post: 120656" data-attributes="member: 4923">I think it depends how we evaluate the depth of field. The calculator is defining what is in acceptable focus through math. I agree that the physics of the lens does not change. If you take a picture of a fence at 45 degrees with that 85mm and 8 fence posts are in focus, that will not change no matter how we crop and enlarge. It is physics and history and we can't change the focus as shown in that picture. BUT... as we zoom in on that image (like dx), our perception changes. Zoomed in a little, that first and last fence post might not look as sharp any more. So maybe at zoom, only 6 posts are in acceptable focus at that level. The picture hasn't changed, the depth of field has not changed but our subjective opinion on what is in focus has changed as we zoomed in. The calculator is doing the same thing, it's just putting a number on it and making a yes/no decision.</blockquote>

[QUOTE="nickt, post: 120656, member: 4923"] I think it depends how we evaluate the depth of field. The calculator is defining what is in acceptable focus through math. I agree that the physics of the lens does not change. If you take a picture of a fence at 45 degrees with that 85mm and 8 fence posts are in focus, that will not change no matter how we crop and enlarge. It is physics and history and we can't change the focus as shown in that picture. BUT... as we zoom in on that image (like dx), our perception changes. Zoomed in a little, that first and last fence post might not look as sharp any more. So maybe at zoom, only 6 posts are in acceptable focus at that level. The picture hasn't changed, the depth of field has not changed but our subjective opinion on what is in focus has changed as we zoomed in. The calculator is doing the same thing, it's just putting a number on it and making a yes/no decision. [/QUOTE]

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