 Manish Issar |
Hyperfocal Distance Hi All, Can somebody explain me what a hyperfocal distance is and how to calculate this distance for your camera? Comments welcome. Thanks.
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John P. Sandstedt |
Hyperfocal distance is a variant on depth of field. Because your camera focuses on an image plane, there is a zone of acceptable sharpness in front of and behind the focal plane. Generally, the zone of acceptable sharpness extends one third in front of the focal plane, two thirds behind. Therefore, if you focus at infinity all of the "two thirds behind the focal plane" is lost - since everything to infinity is sharp anyway. To take advantage of hyperfocal distance, an optical property of the lens, you actually focus at a distance in front of the desired focal plane. You'll achieve acceptable focus in front of the plane of focus and behind it. Non-zoom lenses have markings to allow you to focus and re-set for hyperfocal distance. These markings do not exist for zoom lenses. Since it's an optical property, hyperfocal distance can be calculated. Here's the formula: HFD = F X F/f X d, where HFD = hyperfocal distance You can get a great HFD table at: Hope this helps.
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John P. Sandstedt |
Sorry - the circle of confusion should be 1/1000 of the focal length; but use 1/200 inch as a starting point.
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Tony Sweet |
First off, hyper-focal is a function of short or wide-angle lenses, practically from 20mm to 35mm (approx.). A quick method that many professionals use, since we seldom have time in quickly fading natural light to consult charts, is to focus 1/3 into the film plane at f/22. This does NOT mean 1/3 into the scene. It means 1/3 from the bottom of the picture space (in the finder). Focusing at that point, at f/22, is where you'll achieve your maximum sharpness. Using charts for more exacting measurements for critical sharpness is great for controlled light situations where one has the luxury of time, e.g. studio product photography.
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John P. Sandstedt |
Tony, I realize I'm not a pro, but I'd hate to be forced to use a wide angle lens to achieve maximum depth of field via use of hyperfocal distance. Since it's an optical property, it's available with all lenses, and I've used it many times with telephotos and normal lenses, as well as wide angles. In fact, with wide angles, it might not even be needed! John
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Tony Sweet |
Hi John: Without the use of a short telephoto tilt/shift, maximum depth of field from near to infinity is not possible with a telephoto lens as far as I know. If you have an example of an image with extreme depth of field that is sharp from 1 foot to infinity, I'd be very interested in seeing the image uploaded.
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John P. Sandstedt |
I submitted this as part of my NYIP requirements for HPD. No one ever said sharp from 1 foot to infinity; if you re-read my first repsonse, I noted DOF at 1/3 in front of focal plane and 2/3 behind. By focussing at infinity, lots will be lost. Regards,
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Tony Sweet |
Nice, well composed image! But, it's hard to tell what's happening on a TV screen. I would need to see this image through a high powered loupe to see if it's tack sharp from the swan to the trees in the back. Have you louped this image? Although, the 1/3:2/3 ratio is correct, it works best in the 20-35/40mm range. Sorry to keep taking issue with you on this, John, but telephoto lenses are not the right tool for maximum depth of field. They are not designed for that function. Don't take my word for it, ask around.
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Bill Boswell |
Here is a great site to print off a customer Hyperfocal chart for your lenses: http://www.johnhendry.com/gadget/hf.php
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