The MC4 features a 4-element 4-group design with multi-coated lens elements and fully automatic diaphragm coupling. With the Kenko TelePlus MC4 DGX your prime lens' depth of field is reduced by 1/1.4 but retains the prime minimum focusing distance. TelePlus converters have genuine Gated Array IC (Integrated Circuitry). This means that signal integrity is maintained between the camera body and lens and autofocus will work properly on lenses with apertures of F/4 or brighter. On lenses with smaller f-stop values manual focusing may be necessary. The updated circuitry also allows for the exposure meta-data to be recorded by the camera more accurately.