In response to the feedback from professional photographers, this lens has experienced a drastic weight reduction making it the lightest in its classes*. This is done by improving the optics and mechanical structure of this lens. The EF 300mm f/2.8L IS II USM uses 2-fluorite-lens-elements to replace the 1-fluorite-and-2-UD-lens-elements design as in their predecessors, and replace the front flare reducing Meniscus lens by SWC (Sub Wavelength Structure Coating) for better elimination of ghosting. These optical refinements successfully make the lens lighter and, at the same time, provide more superior image quality. On the mechanical side, in order to remove excessive weight, the new lens barrel is designed by precise computer simulation technology. As a result, magnesium alloy can be used more effectively to make the lens lighter and retain strength. Besides, Titanium is used for some parts to further reduce weight. Together with the new compact Image Stabilizer (IS) unit, the EF 300mm f/2.8L IS II USM is 341g lighter (approximately 12.7%) compared to its predecessors.
Apart from weight reduction, another development objective is to bring unrivaled image quality. Adopting a completely new optics design of 16 lens elements in 12 groups with Fluorite lens elements to drastically minimize secondary chromatic aberration commonly found in telephoto shooting, this lens ensures excellent image quality with high levels of image resolution and contrast. The new optical design is also perfectly compatible to Extender EF 1.4X III and EF 2X III, lower color blur and higher AF accuracy are obtained when in use. The lens features SWC which effectively reduces ghosting when there is a strong light source in image. The maximum magnification has been improved to 0.18x by reducing the minimum focusing distance to 2m, and this lens empowers photographers with greater shooting flexibility.
A newly designed optical IS unit is featured in the new lenses. With Canon’s expertise in developing IS unit, the new design uses rolling balls in the sliding parts of the compensation optics barrel to make an ultra-minimum-friction structure and a Voice Coil Motor as the locking mechanism. These result in a lighter, more compact IS unit that provides an effective 4-stop shake compensation to maintain telephoto shooting stability even under dim environment, enabling photographers to shoot with ease in different lighting situations.
In addition to the existing IS Mode 1 for general shooting and IS Mode 2 for panning shots, the new lenses feature a new IS Mode 3. Among these modes, the IS Mode 2 is improved with new algorithm that achieves higher precision in shake compensation during panning shots by detecting the panning direction more effectively. The new IS mode 3 is specially catered for photographers who use IS to capture dynamic objects. When the shutter release button is half-pressed in IS Mode 3, the IS compensation lens will be locked electrically at the center of the optical axis, image in the viewfinder moves more naturally without any undesired IS effect, while shake compensation keeps being calculated. Only when the shutter release button is fully pressed, the IS lens will be activated immediately and uses the data calculated to provide shake compensation during exposure.
This lens inherits the features highly praised by professional photographers, which include the AF-Stop Button that caters for different focus tracking needs and the Focus Playback Ring that works with focus reset function to instantly switch to the preset focusing distance. To facilitate EOS Movie shooting which is highly rated by filmmakers today, a new Power Focus (PF) Mode is invented to provide a professional manual focusing effect during video shooting. By turning the Focus Playback Ring, manual focusing will be operated smoothly by the built-in USM (Ultrasonic Motor). The focusing speed can be operated at low or high speed, depending on how far the Focus Playback Ring is turned.
To help photographers conquer even the adverse outdoor conditions, fluorine coatings are applied to the front and rear elements of the lens to make it extremely oil-and-water-repellent. Better images can be expected resulting from clean lens which can be easily maintained. Water and dust resistant construction# is adopted on all switches, buttons, rings and drop-in filters for more reliable performance under different conditions. A new security slot is also installed for the first time under the cap of the tripod mount lock nut for attaching a notebook wire-type security lock^ as an anti-theft precaution. The lens can be securely locked when the users are away from the workplace.
* As of 31 August 2011, including the weight of lens and tripod mount
# With EOS-1D Series and EOS-1V, however it is not recommended for use under rain
^ Security wire is not included
