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Canon has developed the EF-S 18-135mm F3.5-5.6 IS STM and EF 40mm F2.8 STM lenses with stepper motors for fast, quiet operation when shooting video. The 18-135mm STM is an extended standard zoom for APS-C DSLRs, while the 40mm STM is a pancake prime lens for full frame and APS-C cameras. Both lenses feature stepper motors, to enable fast, quiet focus, particularly with the contrast-detection method of autofocus used for live view and video. They also both have electromagnetic diaphragms - allowing smooth and accurate control over aperture for video shooting. The lenses will be available from late June 2012, with the 18-135mm STM costing $549 and the 40mm F2.8 STM costing $199.