From the depth of field and the defocus equations of the background, we can derive the following approximate equations for a background at infinity:
b = f ^ 2 / (x_d * N)
DoF = 2 * x_d ^ 2 * N * C / f ^ 2
second the disk size is blurry,
DoF It's the depth of field,
F is the focal length,
x_d is the distance of the subject,
north is the opening F number and
do It is the circle of confusion.
Immediately we noticed that
second can be represented in terms of
DoF and vice versa:
b = 2 * x_d * C / DoF
DoF = 2 * x_d * C / b
Now, since we are behind great blurred background
second, we must consider how it varies depending on the size of the sensor.
x_d, the distance of the subject, is the same for the equivalent image.
DoF It is also the same for an equivalent image, as long as you can achieve the
DoF You are looking for both the full frame and the cut body. What is different is the circle of confusion.
do: divided by the clipping factor in a clipping sensor. Therefore, background blurring is also divided by the clipping factor in a clipping sensor. However, the sensor size is divided too much by the clipping factor in a clipping sensor.
Then, as a conclusion, the amount of blurring of the background as a percentage of the size of the sensor remains the same (with the size of the sensor and the size of the background blurring disk divided by the clipping factor). Therefore, in the full-frame and clipping sensor bodies, an equivalent amount of background blurring is obtained, as long as you can achieve the
DoF you are looking for.
Therefore, we must analyze if it is possible to achieve what is desired.
DoF in a culture sensor body. When mounting a f / 1.8 lens (such as the Canon Nifty Fifty, EF 50mm f / 1.8 STM), it is possible to have a depth of field of just centimeters as shown in this example:
Clearly, we can see in the image that the depth of field is too shallow (image information: focal length of 50 mm, subject distance of 1000 mm, f / 1.8, body of the clipping sensor, which gives a DoF of 27 mm). Therefore, it is generally possible to achieve a sufficiently superficial DoF in the body of a culture sensor.
Now, I must admit that it is easier to achieve an extremely superficial DoF in a full-frame camera, but that is not usually what the photographer wants, as the image of the cactus shows. In addition, full-frame cameras require a longer focal length, and maintaining the aperture number F is not easy with increasing focal length, so it is debatable whether it is really easier to achieve an extremely shallow DoF in a full-frame camera .