Autofocus in video mode on the new Canon T4i wouldn't be all that useful without some lenses designed to handle it. That's why Canon is introducing a new STM (stepping motor) line of lenses. Not only are they basically silent, but they are more capable of handling the smooth focus transitions that are required for video autofocus as opposed to photo autofocus -- which is designed to be fast and accurate at the cost of jerky focus movements. The first two lenses they are introducing will be a replacement to the 18-135mm kit lens, and a 40mm f/2.8 pancake.
Here are the specs on the new EF-S 18-135 f/3.5-5.6 IS STM:
- Close focusing distance: 0.39m
- Image stabilization is designed for both photography and video - and will give stability at up to four stops more during photographs
- Employing circular aperture EMD (Electronic drive aperture) mounted close to the original than by the light of the background
- STM (Stepping Motor) AF operation of the motor has dramatically reduced noise and features smooth movement of the AF drive
This is the new 40mm f/2.8 pancake lens, which is about half the size of the Canon 50mm f/1.8:
- Closest focusing distance: less than 1 ft.
- The maximum magnification ratio: 0.18-fold
- Filter diameter: 52mm
- The maximum diameter: 68.2mm
- Length: 22.8mm
- Weight: About 130g
Below you'll find a comparison of the new pancake lens with the Canon 50mm f/1.8. With lenses getting bigger and bigger, they begin to negate the usefulness of a small body. This lens is supposedly going to be relatively inexpensive (thanks to its slower speed), but I'm sure it's going to find its way into plenty of bags as it takes up almost no space. You can also see the new 18-135mm STM lens on the Canon T4i in a photo below.