D.Hussey Offline Upload & Sell: Off
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jcolwell wrote:
The "hyperfocal distance" is 42m away. That's not necessarily the same as the "ideal focal point".
The hyperfocal distance represents the distance at which everything from half that distance to infinity will be in acceptable focus. In this case, from 21m to infinity. This concept is based on the "circle of confusion" which represents how much out-of-focus (OOF) you can tolerate while the result still looks acceptable. The diameter of the circle of confusion (Dcc) is related to the photo's original format size (i.e. FF DSLR, m43, medium format...), the size of the image that is being viewed (e.g. 8" x 12" print, 27" monitor, 20" x 30" poster...), and the distance from which you're viewing the image. IOW, it's based on magnification. The value of Dcc = 0.03mm represents an original image of 36mm x 24mm (i.e. full frame DSLR), printed at 8" x 12", and viewed from three or four feet away. If you get a lot closer, you'll notice that some areas that appeared to be in focus from "normal viewing distance" now appear slightly OOF. Many people, including Harold Merklinger (see below) say that if you want infinity to be in focus, then you should focus at infinity.
Merklinger, "The INs and OUTs of Focus" http://www.trenholm.org/hmmerk/TIAOOFe.pdf
BTW, many older "Alt" lenses (and some newer ones, too) have hyperfocal distance markings on them. For example, the Leica Summicron-R 50mm f/2 lens shown below is set at f/8 (aperture values on bottom ring with white dot "index" just above), and the ring of aperture values just above the index shows the range of focus distances (next ring up) that are "in focus". In this example, the lens is focused to 10m (or just about), and the left and right values of 8 on the hyperfocal scale show acceptable focus from about 5 m to infinity....Show more →
Okay, I get it now
Thanks for the explicit and easy to grasp clarification
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