Traditional Culture Encyclopedia - Photography and portraiture - What is the 0.7X magnification of the viewfinder of SLR camera?

What is the 0.7X magnification of the viewfinder of SLR camera?

The image formed by the viewfinder of SLR camera is a real image, assuming its size is 4CM*4CM, but there is a lens in front of the pentaprism of the viewfinder, which can change the size of the real image and make it clearer. The change rate is 0.7, that is, 2.8CM*2.8CM.

Virtual image: that is, its light can only be imaged after being focused by human eyes.