Hyperfocal distance Is the distance the lens is focused when the back edge of the field of focus lies at 'infinity' for a given geometric aperture.
When the lens focuses on infinity, not only objects located at infinite distance from the lens, but also many objects that are closer to the conditional infinity of the lens are sharp. In this case the concept of infinity is conditional, you do not need to think that the lens should focus on real infinity, which is located far beyond the moon and stars, near the far boundary of our universe. For many lenses, a focusing span of several meters is already called infinity. Each lens has your own hyperfocal distance, which means its own distance with which all objects will be sharp in the image.
Now many users of digital and digital-mirror, mirrorless and interchangeable lens cameras are hard to understand the meaning of the width of the field of focus, which is commonly called DOF - гbast рkeenly иimaged пrostranstva. On modern cameras and lenses, important indicators of focus distance and depth of field are often removed. Old lenses, and some modern ones, have special scales by which you can determine at what focus distance the lens is mounted. The focusing distance, for example, at a value of 2 meters, means that only those objects that are 2 meters away from the camera will be sharp. However, due to the fact that the sharpness zone has a certain length, the depth of field scale shows the distance to the object and behind the object, which will also be sharp.
DOF depends heavily on:
- Aperture F, because DOF is indicated only for certain aperture values. In the example above, the aperture is set to F / 11 using the aperture control ring. The lens is focused on about 1.5 meters, the depth of field scale shows that all objects that are at a distance of 1 to 2 meters will be sharp. If we set the value of F / 22 we will get the depth of field from 0.7m to infinity.
- Focusing distances... The shorter the focusing distance, the thinner the DOF. Conversely, the larger the focusing distance, the wider the DOF.
- Influenza indirectly affects matrix size camera (photosensitive element). More than matrix size, the wider the viewing angle and the closer you need to get to the subject, which, in fact, rests on the second point. Therefore, they claim that full-format cameras blur the background more strongly than cropped ones. Speaking rudely, the more crop factor, the more DOF.
Important: focal length has very little effect on the depth of field, but due to the strong visual effect, it seems that the focal length, too, greatly affects the depth of field. I would say that focal length affects on the strength of the blur foreground / background (its visual perception), but it affects the width of the depth of field very little (with the same layout of the same frame with lenses with different focal lengths). At a constant shooting scale, the depth of field does not change when using lenses with different focal lengths.
Very important: DOF is a relative concept. It is connected with what is considered sharp and what is considered not sharp, and therefore the boundaries of depth of field are conditional, just like the marks for depth of field on the lens scale.
Due to the fact that when focusing at distances less than the conditional infinity, only some of the objects in the frame will be sharp, the rest will not be sharp, in which case they say that the foreground (near) and far (background) planes are blurred. If you focus on the hyperfocal distance, then only the foreground may not be sharp, and the background 'rests' against the infinity of the lens and becomes sharp.
The hyperfocal distance has one feature - if you set the focus of the lens not to infinity, but to the hyperfocal distance, then you can get maximum depth of field from a certain value in the foreground to infinity. This is a very important property when photographing landscapes and more.
It is easy to imagine the depth of field in the form of two planes that form a volume in which everything becomes sharp. We live in a three-dimensional world, and therefore it is easier to imagine a real 3-dimensional situation. The depth of field forms such a sharp area, enclosed between vertical planes, not only the snow, but also the clock (not only grass, but also the raven in previous photographs) become sharp.
Important feature: when we focus on extremely close distances (on MDF), then the depth of field decreases. It is easy to imagine a narrowing of the distance between the planes shown in the picture above. When we begin to focus the lens at distances close to infinity, the depth of field increases. This is easy to imagine by expanding the distance between the planes. When we get to the hyperfocal distance, the plane farthest from us will disappear, go to infinity, and the image will be sharp from the hyperfocal distance to infinity.
Important feature: in order to get a picture of objects at infinity, it is not always necessary to set the focus value on the lens to the limit value of infinity. You can do with a hyperfocal distance. With closed apertures, the hyperfocal distance can be greatly reduced.
Important feature: many lenses, both new and old, have a flight beyond infinity, which means that the lens can focus on infinity, and if you twist the focus ring further, infinity will not be sharp. This is a special idea in the design of the lens, which is designed to compensate for the stretching of the helicoid at different temperatures and will focus on infinity in both winter and summer. Also, many lenses have infinity so that they can be used without problems on different cameras with different working lengths, and also because of the design features of some zoom lenses.
Some features of lenses
- The larger the telephoto lens, the greater the hyperfocal distance. For example, telephoto Nikon ED AF Nikkor 300mm 1: 2.8 It has GR for F / 2.8, equal to several hundred meters.
- The smaller the focal length of the lens, the less GR. For example, a super wide angle lens Zenithar 16mm F2.8 MC Fisheye It has GR for F / 2.8 equal to approximately 1,5m.
- The closer the aperture is, the smaller GR. Roughly speaking, on covered apertures using super wide-angle lenses, you can generally forget about focusing.
- Get a small telephoto lens GR pretty hard.
The hyperfocal distance can be easily felt when working with wide-angle and ultra-wide-angle optics. The wider the field of view of the lens, the shorter its hyperfocal distance. This effect can be seen even when using the kit 18mm lens. At the 18mm position, the autofocus only rotates the focusing ring slightly, since in most cases the lens works 'at hyperfocal' and everything beyond a few meters is already sharp, and the camera does not need to refocus. I don't use grip calculators, it's easier for me to figure out by eye or from personal experience how the lens will behave. Due to the short hyperfocal distance of ultra-wide angles, it is very convenient to work with the latter in manual focus mode.
Understanding how focusing, depth of field and hyperfocal distance work can help create the desired effect in photographs, improve volume transfer, and help in choosing a lens. In general, with infinity you need to conduct your own experiments in order to 'probe' and understand everything.
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