Photography magnification can be a confusing and complicated topic so I thought I would write a simple definition and provide a visual example of what one can do with the right technology. The magnification of a lens means how large (or small) a subject can be reproduced on the image plane. In the film world the image plane is the film itself. In today’s digital photography world the image plane is the digital sensor. There are many sensors and sensor sizes but we will leave that topic for another day.
If a subject of length X results in an image of length Y in the image plane then the magnification is defined to be Y/X. So, if we have a subject that is 10mm in length and it has a length of 10mm on the image plane then the magnification is 10/10=1x. If the length of the subject on the image plane is 20mm then the calculation would be 20/10=2x. Not all lenses can capture this type of image. You will need a “Macro Lens” in order to capture “life-size” images (1x) on your image plane. In addition, capturing magnifications higher than 1x requires even more sophisticated setups and post-processing techniques.
The Diptych below of a pencil and pencil tip was taken with a “full frame sensor” camera (image plane measures 36mm x 24 mm). Its image plane size is equal to an old 35mm film frame, thus the name. The thickness of the pencil is about 7mm and it measures 7mm on the image plane so its magnification is 1x. The image of the pencil tip measures about 5mm high in real life and it measures about 27mm on the image plane. So, its magnification is 5x.
This image was taken with my Canon EOS 5D Mark III using my Canon MP-E65mm f/2.8 1-5x Macro Lens. The camera was set on Manual mode with the aperture set at f/6.3, shutter speed at 1/10th of a second (left image), 2.5 seconds (right image) and the ISO set at 100. I used my light box with LED lighting to photograph both images. Both images were put together with multiple images and I used Helicon Focus to stack them.