The 1:1 Ratio of Macro Photography
Macro photography means creating an image in which the subject is depicted on the digital sensor (or film plane) in its actual size. That means it has a magnification ratio of 1:1, and if you printed an image the same size as your digital sensor (36mm x 24mm for a full frame DSLR), the subject would appear life-size.
The subject shown here was photographed with a 1:1 magnification ratio using a full-frame DSLR camera, and printed with the sensor’s true dimensions. See for yourself that the subject is represented in its actual size.
Macro photography isn’t a magnification but a true representation. However, the macro photograph appears to be a magnification because most prints are made to be much larger than the digital sensor’s size, and you view most images on your monitor at a larger size as well. A macro subject appears huge in an 8x10 photograph compared to its actual size of about 36mm x 24mm.
Because the size of your DSLR camera’s digital sensor is fairly small (relative to most subjects), photographers typically use macro photography when shooting very small subjects. It’s a method for showing detail that would be lost, or unnoticeable if the subject were photographed with less magnification.
100mm, 0.3, f/16, 640