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question about hyperfocal distance

lenses focus hyperfocal distance

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#1 davide sorasio

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Posted 12 October 2015 - 03:54 PM

Hi everybody, I'm still a beginner and I'm having some doubts about hyperfocal distance. Playinng with some DOF charts I've noticed that the hyperfocal distance changes with the aperture and the focal lenght of the lens. For example shooting 35mm 3-perf on a 50mm and at a F2 the hyperfocal distance is 161' and 6", so if focusing for this distance everything from 80' to infinity should be in acceptable focus (please tell me if I'm wrong about it), but what if the hyperfocal distance is something like 400', most lenses do not have a mark for it, so which distance should I be focusing for?

Thank you so much in advance for the help!


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#2 Satsuki Murashige

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Posted 13 October 2015 - 01:21 PM

Hyperfocal distance is the where you set the focus on the lens when you want the depth of field to cover from a near point to infinity. Depth of field varies depending on the lens focal length, focus distance, aperture, and circle of confusion selection, so if you change any one of those settings then the hyperfocal distance will change as well.

The circle of confusion is the tolerance for acceptably sharp focus, it varies depending on your shooting format, final output resolution and magnification size. So if you were shooting 1920x1080p for web delivery to 15" screens, you can work at a lower tolerance than if you were shooting 35mm anamorphic for a 50' cinema screen - more shots would seem to be in focus with the former even if they are actually slightly out of focus with the latter.

If you are not shooting with cinema lenses that have accurate focus marks, I wouldn't worry about it too much as hyperfocal distance is not going to be of much use to you. As you said, how can you set an accurate focus distance on the lens when there are no marks? Also, nowadays because modern lenses and digital sensors are so sharp, the tolerances as noted in those charts may not be accurate anymore. You really need to test your lens/camera/final delivery output to make sure.

Most 1st AC's today work on the theory that there is one accurate focus mark at any one time in the scene. So the shot is either focused correctly and sharp or it is soft. The depth of field is there to CYA (cover your ass) but it is rarely relied upon for split focus shots anymore because the tolerances are now so low.

Some manual focus still photo lenses (older ones) have rough hyperfocal marks scribed on the barrel, just take them with a grain of salt as they were intended for blowing up 35mm full frame 24x36mm format to a particular print size, which is not really relevant when using them for other purposes.
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#3 Mark Dunn

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Posted 13 October 2015 - 01:56 PM

You'll have noticed that the near limit of DoF is exactly half the set distance.

Here's my Canon 50mm. set at 5'. The DoF marks are below the scale. So DoF extends from about 2'6" to infinity at f16.

http://s5.photobucke...C01125.jpg.html


Edited by Mark Dunn, 13 October 2015 - 02:00 PM.

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