Relationship between lens magnification and zoom factor

Optical zoom is the focal length of telephoto end divided by the focal length of wide-angle end. In order to take care of it, the card machine or telephoto machine usually starts at 28-38 mm, so as long as you know the zoom multiple, such as 5 10, 20 times the viewing angle, you will probably have an idea, but the lens of the SLR can be changed. Like the 70-200, it has a zoom of about 3 times, but the viewing angle of 70 mm at the wide-angle end has been compared with some SLR. The telephoto end of sleeve 18-70 has the same viewing angle. For example, some machine guns 1200- 1800 only have the initial focal length of 1.5 times zoom, and the equivalent focal length of telephoto camera1200 at 24 times zoom is less than half of the wide-angle end of this lens.

Lens magnification refers to that at macro, the actual object of 1 cm is imaged as 0. 1 cm on the negative. Generally, the zoom magnification of Canon 100 micron1200mm focal length is1:/kloc-0.