If you want to calculate the depth of field you need some values (like the aperture) and a few formulas. This allows everyone to calculate the depth of field themselves, at least an approximate value.
It is not unimportant for the correct sharpness in the image to know something about the Depth of Field to be expected. And you can calculate the sharpness or Depth of Field in the image yourself. But if you don’t want to calculate any equations yourself, then my small tool for calculating the Depth of Field can help. You enter or select the most important values for the calculation and the small calculator shows you the result. Note, however, that the result is only an approximation!
For the calculation you need the following factors: the distance to the object, the focal length, the aperture and also the sensor or its size is important (e.g. full format or a crop). Information about the sensor of your camera can certainly be found in the camera manual.
Further information regarding the approximate value and the subject Depth of Field can be found below after the Depth of Field calculator :)
What is the Depth of Field?
An optical system, such as a camera, can only focus on one plane at a time! Depth of Field refers to the area of an image that is still perceived as sharp by the observer, namely the area in front of and behind the plane of focus. For example, you can use this game with the sharpness to release it. In this way, you can ensure that a background is in the blur, i.e. that it is displayed out of focus. And your motive is displayed in a really sharp way in the picture. As in the example with the piano, where not only the background but also the foreground is blurred. Used in this way, the Depth of Field creates a special depth or depth effect in the image. And so the flowers form a beautifully delimited motif. So you achieve a big effect with a small stylistic device.
This effect is created by the combination of aperture, focal length, distance to object and sensor. A somewhat complicated calculation. The aperture and focal length are still visible on the camera, which sensor the camera uses can be looked up in the manual. And, well, you really have to measure or estimate the distance, then it works with the right depth of field to the subject.
With the aperture you can usually influence the Depth of Field the most. The rule of thumb here is: the smaller the aperture or f-number (i.e. the larger the aperture), the greater the Depth of Field. In other words, the smaller the area in the image that is recognized as sharp. Of course, this also applies the other way round. The larger the aperture or the f-number, the smaller the aperture), the lower or smaller is the degree of Depth of Field. The extent of the blur is therefore much greater with the aperture as wide open as possible.
But how does sharpness get into the background? If you really want the background to get more sharpness or at least almost sharpness, you have to close the aperture (large number of apertures). For more sharpness in the background, the focal length and the distance have to fit.
And with the following form you can calculate the Depth of Field.
Why only an approximate value?
The calculation of the Depth of Field can only be carried out exactly if the calculation is carried out using a completely predefined camera system with fixed (mechanical/optical) dimensions. The lens, for example, plays a not inconsiderable role here. A 50mm lens (fixed focal length) from manufacturer A may have other relevant characteristics than a 50mm lens from manufacturer B. Internal or external focusing also makes a difference. Further camera system dependent values are also necessary to calculate the exact Depth of Field, so a general tool can only calculate approximate values. But when is the Depth of Field needed to the exact mm?
And, can you always be sure that an aperture f8 is always exactly the same aperture (or the same aperture opening / diameter) for different cameras? Or whether there are not minimal differences, which are quite noticeable with a calculation?
- Depth of Field: The area that is perceived as sharp by the human eye
- Distance Point: The distance from the lens to the end of the area perceived as sharp
- Near Point: The distance from the lens to the beginning of the area perceived as sharp
- Behind the focal plane: The area perceived as sharp behind the focal plane
- Before the focal plane: The area perceived as sharp in front of the focus plane
The near and far point is usually calculated from the last lens of the lens. Depending on the type of lens, however, this distance is calculated from an area in the middle of the lens or from the first lens.
If you want to practice mathematics or simply immerse yourself in the depth of matter, Wikipedia offers comprehensive information on how to calculate the Depth of Field.