Yin Yan Flash, what do you think of the following indicators?

The following table refers to the effective flash distance of the flash under each aperture. The relevant calculation formula is as follows: GN=F×S, that is, flash index = aperture× object distance (that is, the distance between the subject and the camera film /CCD is not very accurate, but only an estimate). For example, if your flash index is 32 and the distance between the camera and the subject is 1 m, then you can get F=GN/S according to the propaganda transformation, which is the flash index. If you are using F8 aperture now, how far away from the subject can you take accurate exposure photos? 32 divided by 8 equals 4, which means 4 meters is enough. I wonder if the landlord understands.

This formula is mainly used in the early film SLR. The early flash can't be well linked with the photometric exposure of the camera, so it can't be achieved quickly. So we have to work out the desired data according to this announcement. Now the camera supports the flash very well, just look at many electronic contacts, so this formula is basically unnecessary, because the value calculated according to the formula is not 65,438+000% accurate, just a reference.