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Photography Q&A
Does standing further back & zooming in increase the acceptable focus zone?
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<blockquote data-quote="WayneF" data-source="post: 551021" data-attributes="member: 12496"><p>If saying depth of field remains roughly the same, it seems important to specify "to get the same frame", which you did specify. The rule of thumb (with same aperture) is "same subject size is the same depth of field". And it is roughly true, generally, within limits. </p><p></p><p> Here is a more indepth look at it:</p><p><a href="http://www.dofmaster.com/dof_imagesize.html" target="_blank">Depth of Field When Image Size is Constant</a></p><p></p><p></p><p>But it might help understanding to note that what it is actually largely about is the <strong>degree of magnification</strong>, about how well we can actually see the blur in the image.</p><p></p><p>Generally, to be usable knowledge, it seems enough to know that DOF increases with these basics, which we should all know:</p><p></p><p>Stopped down aperture (actually affects Circle of Confusion, sharpness)</p><p>Shorter focal length (is just less magnification of CoC)</p><p>Greater focus distance (is just less magnification of CoC)</p><p>and if switching cameras, with a smaller sensor or film size (because it necessarily uses a shorter focal length, and affects enlargement)</p><p></p><p></p><p>CoC is an easy obvious concept, once we've seen it.</p><p><a href="https://en.wikipedia.org/wiki/Circle_of_confusion" target="_blank">http://en.wikipedia.org/wiki/Circle_of_confusion</a></p><p></p><p>A DOF calculator takes all these things into account, but another thing we should know is that while DOF can easily be computed out to many decimal places, but in real life, the numbers are pretty vague, because it also depends on a judgement about typical eyes, in a specific viewing situation (estimated to be what can be seen from 35mm film enlarged to an 8x10 inch print viewed at 10 inches). It is about enlargement, but our own viewing situation/enlargement is rarely ever the same. What we can see (DOF) also depends on enlargement of the result. It is more a concept than exact numbers. We should treat the numbers as ball park numbers, perhaps more or less appropriate to our own case. But we should know how to increase or decrease it, and to position it to where we need it to be.</p><p></p><p></p><p></p><p>It's just human nature to try to help, even if maybe we don't really know. I'm guilty too, I think we all are. We like to explain how we think it ought to be, when maybe how it actually is may be different. I see a post asking about some standard feature on maybe an Acme X4000 camera, and I think I know and want to help, but I have to realize I've never seen an Acme. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /></p></blockquote><p></p>
[QUOTE="WayneF, post: 551021, member: 12496"] If saying depth of field remains roughly the same, it seems important to specify "to get the same frame", which you did specify. The rule of thumb (with same aperture) is "same subject size is the same depth of field". And it is roughly true, generally, within limits. Here is a more indepth look at it: [URL="http://www.dofmaster.com/dof_imagesize.html"]Depth of Field When Image Size is Constant[/URL] But it might help understanding to note that what it is actually largely about is the [B]degree of magnification[/B], about how well we can actually see the blur in the image. Generally, to be usable knowledge, it seems enough to know that DOF increases with these basics, which we should all know: Stopped down aperture (actually affects Circle of Confusion, sharpness) Shorter focal length (is just less magnification of CoC) Greater focus distance (is just less magnification of CoC) and if switching cameras, with a smaller sensor or film size (because it necessarily uses a shorter focal length, and affects enlargement) CoC is an easy obvious concept, once we've seen it. [URL="https://en.wikipedia.org/wiki/Circle_of_confusion"]http://en.wikipedia.org/wiki/Circle_of_confusion[/URL] A DOF calculator takes all these things into account, but another thing we should know is that while DOF can easily be computed out to many decimal places, but in real life, the numbers are pretty vague, because it also depends on a judgement about typical eyes, in a specific viewing situation (estimated to be what can be seen from 35mm film enlarged to an 8x10 inch print viewed at 10 inches). It is about enlargement, but our own viewing situation/enlargement is rarely ever the same. What we can see (DOF) also depends on enlargement of the result. It is more a concept than exact numbers. We should treat the numbers as ball park numbers, perhaps more or less appropriate to our own case. But we should know how to increase or decrease it, and to position it to where we need it to be. It's just human nature to try to help, even if maybe we don't really know. I'm guilty too, I think we all are. We like to explain how we think it ought to be, when maybe how it actually is may be different. I see a post asking about some standard feature on maybe an Acme X4000 camera, and I think I know and want to help, but I have to realize I've never seen an Acme. :) [/QUOTE]
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Does standing further back & zooming in increase the acceptable focus zone?
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