AF Motors

Fujifilm X-mount lenses use three types of autofocus motor. The motor type affects focus speed, accuracy, noise, and video suitability.

DC (coreless motor) is the oldest design, found in early XF lenses. It uses a small DC motor with a gear train. Focus is adequate for stills but audible and slower than modern alternatives. DC lenses hunt more in low light and are not ideal for video due to motor noise.

STM (stepping motor) is a stepper motor that moves in precise increments. It is quieter than DC and well-suited to video because it produces smooth, silent focus transitions. STM lenses are common in mid-range XF and XC lenses. Focus speed is good but not class-leading.

LM (linear motor) is Fujifilm’s fastest and quietest AF technology. It uses electromagnetic force to move the focus group directly, without gears. LM lenses focus almost instantly, track moving subjects reliably, and are virtually silent. All recent flagship XF lenses (f/1.4 R LM WR series, XF 50-140mm, XF 150-600mm) use linear motors.

For sport, wildlife, and video, LM lenses are strongly preferred. For general photography, STM is more than adequate. DC lenses still take sharp photos but may struggle with fast action.