Created by Canon and originally introduced into its broadcast ENG lenses, Internal Focus is a multi-group technology that uses a floating optical system to optimize control of chromatic aberrations and reduce focus breathing effects. Designated as "IFpro" in the new YJ20x8.5B KRS long-zoom portable 2/3-in. lens and new YJ13x6B Series wide-angle portable 2/3-in. lenses, Internal Focus enables the front end of the lens to remain stationary as the internal elements move during focusing. IFpro technology enhances optical performance and provides multiple user benefits, according to Canon, including improved performance in changes in object distances, decreased lens flare with the use of a square lens hood, a higher level of creative filter options, and the ability to use optical accessories attached to the front end of the lens.
The new YJ20x8.5B KRS IFpro lens and the new YJ13x6B Series lenses also incorporate Canon's newly developed optical materials in combination with new lens-element design innovations and multilayer coatings. The new YJ20x8.5B KRS long-zoom portable lens and the new YJ13x6B Series wide-angle portable lenses feature a horizontal field of view of 54.7 degrees and 72.5 degrees, respectively. The company says that the optical optimization strategies of all three lenses achieve an excellent MTF (Modulation Transfer Function) profile over their entire respective image planes, minimizing chromatic aberrations and maximizing image contrast.
Canon says that the new YJ20x8.5B KRS long-zoom portable IFpro lens offers the widest focal length (8.5mm) and highest zoom ratio (20x) of any lens in its class, in addition to the fastest servo zoom speed (1.2 seconds, end to end). Designed to achieve a compromise between the demands for high sensitivity (the lens' maximum relative aperture is f 1.8) and mobility in lightweight hand-held cameras, the new YJ20x8.5B KRS weighs 2.58 lbs., 11 percent lighter (and 5mm shorter) than its predecessor, the YJ19x9B KRS.
The new YJ13x6B KRS portable IFpro lens delivers the highest zoom ratio (13x) and widest focal length (6mm) of any Canon lens in its class. It also features a 1.2-second, end-to-end servo zoom speed. The alternate YJ13x6B IRS model, meanwhile, has a 2x Extender that facilitates a focal range of from 12mm to 156mm. The YJ13x6B Series balances sensitivity (this lens' maximum relative aperture is f 2.0), mobility, and a wide field of view for use with lightweight hand-held cameras. The YJ13x6B KRS weighs 3.39 lbs., which is 11 percent lighter than the YJ12x6.5B KRS that it replaces.
The YJ13x6B IRS weighs 3.83 lbs., which is 9 percent lighter than its predecessor YJ12x6.5B IRS. In addition to decreased size and weight, Canon reports that they have engineered additional ergonomic design innovations that further improve the price-performance advantages of its three new IFpro lenses. All three lenses feature a new, smaller drive unit that is designed to not only fit into the palm of the user's hand more comfortably, but also improve the feeling of unity between the drive unit and the lens. These drive units, featuring a grip support and ribbed surface, are tilted at a particular angle to order to achieve a better balance and to provide more comfort and reduce operator fatigue. The new drive units featured in the new lenses also help make possible greater levels of precision and control, including control of the exclusive Canon Shuttle Shot feature, which facilitates zooming back and forth between any two focal length positions. Control of Shuttle Shot can be allocated to three different buttons using a DIP switch, depending on the preference of the user.