[font color=\'#000000\']1. What then is the distance that is half way to infinity?
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Not completely sure I understand the question. The "half" refers to the distance between the camera and a point of focus which is at the hyperfocal distance. I'm not aware of any concept dealing with something half way to infinity.
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2. DOF does not have to assume a viewing distance of the print or the print size. I can easily select what I want the final print to look like and then calculate the rest.
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Yes it does. viewing distance and print size are what drives setting the COC, which is a term of the DOF calculation -which as you point out next is clearly defined.
Maybe you could walk me though the process of "selecting what the final print should look like and calculating the rest"?
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DOF is a defined term. If I make a larger or smaller print, or view a print from nearer or farther, the DOF of the print changes. The closer I get, the less the DOF for a given print size. For a given viewing distance, the larger the print, the smaller the DOF.
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I agree.
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I understand how the DOF preview button works. What I was trying to say is the dimmer the image in the view finder, the more difficult is to see what is and isn't in focus. Focus may appear acceptable in the view finder stopped down to f/22 partly because I can't see the image very well.
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At f22 and I use the DOF preview, I can't tell what's in or out of focus either.
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3. Agan, I understand how the DOF preview works. What I was wondering or asking was, does the previewed scene DOF really mimmic the results I expect to get on the final print?
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Dimness aside, what's in focus in the viewfinder will be in focus on the sensor. What appears in focus in the view finder or the sensor may not appear in focus on a 40x60 inch print, but may very well appear in focus on a 8x10, as your point #2 indicates.
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4. I agree with the "relativeness" of the DOF. But if I want to really control what will be acceptably in focus and what will not appearto be focused, I cannot rely on the values of COC, image size, viewing distance, etc. assumed by my lense/camera maker. Nor do I have too. If I want an image that appears in focus between 50 feet and infinity (scene dimensions) on a 20x30" print viewed from 10', and I want subjects closer than 50' to appear out of focus, I can do that much more predictably than focusing half way between 50' and infinity (waht ever that distance is) and stopping down to f/11 or f/16.
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Technically you could rely on modifying the COC according to you printing/viewing intentions, but it would probably be more trouble than it's worth. I agree that there are better methods of determining what's in or out of focus, than what you described. Is the more predictable method you mention using the DEP mode?
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