What is hyperfocal distance? How to use hyperfocal distance?

There are many photographers who need to get the maximum clear range-depth of field when taking pictures. They often know that the smaller the aperture, the better, but they don't know how to apply hyperfocal distance, especially on zoom lenses.

Advertisement: d_text When the lens is focused at infinity, the nearest limit of the depth of field near the camera is called hyperfocal distance. When the lens is focused on the hyperfocal distance with a certain aperture, the depth of field ranges from 1/2 to infinity. Hyperfocal distance is the fastest way to get the maximum depth of field or control the clear range of an image.

For a lens with a Jing Shenbiao scale, it is very simple to determine the hyperfocal distance: just focus on infinity, and then you can see the depth of field range from infinity to a point close to the camera indicated by the used aperture from the Jing Shenbiao of the lens. The distance from the camera to the depth of field is hyperfocal distance;

However, not all lenses have Jing Shenbiao, and the depth of field obtained by hyperfocal distance will change due to the lens focal length, aperture value and your setting of image definition. Therefore, "fuzzy circle" is introduced into the calculation of depth of field and hyperfocal distance as a factor of clarity. A' fuzzy circle' is the diameter of a real light spot that cannot be distinguished by human eyes. In fact, no one can distinguish a point with a diameter less than 0. In the photo with a distance of 25 cm 1 mm. This 0.l mm diameter takes its reciprocal, that is,11,which is equal to10 per mm, and can be used as the starting point to distinguish the number of lines per mm. ..

The formula for calculating the hyperfocal distance of a specific fuzzy circle is:

H=F2/Cf Here, H is the hyperfocal distance, F is the focal length of the lens, C is the blur circle, and F is the aperture used.

In normal use, the diameter of the fuzzy circle is generally set to 0.05 mm, thus simplifying the above formula to H= 1000F/f, and we can accurately know the hyperfocal distance used by any lens combination with focal length and aperture only by simple oral calculation. If we use a 50 mm lens with f/ 16 aperture, then substitute the above formula and calculate it in millimeters. The result is 50000/ 16 = 3 125mm, which means its hyperfocal distance is just over 3m.

Now that we have mastered the above calculation method, we can easily calculate the depth of field under any conditions through the following simple formula.

Depth of field near limit =HD/H+D Depth of field foreground = HD/h-d.

Here, h is hyperfocal distance and d is the focus distance. With this information, we can ensure sufficient depth of field before and after the object by arranging the object in the right position.

In the schematic diagram of this paper, the focus of the above picture is on 3 meters, which is hyperfocal distance. At this time, the near limit of the depth of field is1.5m, and the far limit of the scene is infinite. The following picture focuses on L.5m, and hyperfocal distance is still 3m. At this time, the near limit of the depth of field is 1m, and the far limit of the scene is 3m. This legend can limit the clear area to a group of people by shifting the focus from hyperfocal distance to half its distance, so that some scenes can be arranged outside the depth of field.