The EF 100mm f/2.8 Macro USM has markings in yellow to indicate the magnifications as the focusing distance gets closer. Due to its new optical design as well as the use of the Ring USM mechanism, the lens has a shorter traveling distance when it comes to focusing all the way from infinity down to its 1:1 life-size (1x) magnification. The 1x magnification is obtainable at the closest focusing distance of 0.31m/1.02 ft The yellow magnifications markings are at 1:1, 1:1.5, 1:2, 1:3 and 1:5. Beyond the 1:5 magnification index are the 1 and 3 meters as well as the infinity mark. Compare this to the older lens, which has yellow markings from 1:1, 1:1.5, 1:2, 1:2.5, 1:3 and 1:4. Both Macro lenses also have focusing distance limiters, which permit them to have quicker AF operation and cut down on the tendency to hunt when faced with subjects having low or very little contrast. Unlike the older version, the focusing distance limiter of the EF 100mm f/2.8 Macro USM only allows it to be autofocused from two choices: 0.31m to infinity or 0.49m to infinity. The older lens gives users three choices: 0.307m to infinity, 0.307m to 0.572m and 0.572m to infinity. Of course, the traveling distance for the older lens all the way from infinity down to its closest distance is also longer due to the use of the helicoid-type for the focusing method. To give EOS users an idea of how much the magnifications increase as the focusing distance gets closer with the EF 100mm f/2.8 Macro USM lens, just look at these photos below showing the cover of the latest issue of the twice-yearly Buyer's Guide published by Canon Malaysia. At 1 meter/3 ft distance At 1:5 magnification     At 1:3 magnification At 1:2 magnification     At 1:1.5 magnification At 1:1 life-size magnification     With Extension Tube EF 25   As the magnifications and subject's size increase, the depth-of-field at the given aperture decreases even further. For example, at f/2.8 for a normal shooting distance, like portraiture, will give you a depth-of-field zone consisting of a few inches deep. At the 1:2 or 1:1 life-size magnification, the depth-of-field available will be limited only to a few millimeters instead. Even stopping down to f/8 or f/11 at such magnifications will only give you a depth-of-field zone of about an inch or less. Depth-of-field at f/2.8 Depth-of-field at f/5.6     Depth-of-field at f/11 Fill-in flash was used in the above photos to enable a faster shutter speed to be utilized. << Back to Main . 1 . 2 . 3 .