Hyperfocal distance for video - same calculation as for stills?

Started Oct 19, 2012 | Discussions thread
tom
tom
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Re: Hyperfocal distance for video - same calculation as for stills?
In reply to ArtiTO, Oct 19, 2012

Actually cropping does make a difference in calculation of DOF, but not in the size of the circle of confusion which is dependent on the actual lens FL, aperture, and distance.

The reason that DOF is dependent on crop is because as long as you are displaying the image at a fixed size, a cropped image will require a greater magnification of the image, and consequently a greater magnification of the CoC or blur circle.  Remember, DOF is the distance from the focus plane where the blur on the final viewed image is small enough to appear acceptably sharp.  The more you magnify the CoC (which is measured on the sensor), the more blurry it will appear.

In calculating DOF you use the actual lens FL, aperture and distances, but use different acceptable CoC dependent on sensor size (or image size on the sensor if the image is significantly further cropped for video).  Most DOF programs do offer selections for sensor size.  You should also factor in image magnification (to final viewing size) since DOF will be deeper if you are viewing a 4x6-inch print than if you are viewing on a 30-inch monitor, but most DOF programs don't offer that; there may be some that do.

tom

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