| Photographers normally shooting handheld at 1 | | | | and a powerful ring-type USM for fast and silent |
| 250 sec can switch on IS to obtain a similarly | | | | AF. Optical shake is detected by gyro sensors |
| steady and blur-free result with a shutter speed | | | | which provide data to neutralise the shake. Some |
| of just 1/15 second. The inclusion of automatic | | | | EF lenses have two IS modes, including one for |
| panning detection makes it easier for | | | | panned shots to help you enjoy still greater |
| photographers to track wildlife and other moving | | | | photographic freedom. Optical performance of the |
| subjects. Photographers can also enable additional | | | | lens is maintained; although the actual focal length |
| noise reduction for shots captured at high ISO | | | | becomes extended by 1.26X and aperture values |
| speeds. Photographers normally shooting a | | | | are reduced by 2/3 stop. |
| 300mm frame handheld at 1/500s can obtain the | | | | Optically and mechanically, the lens seemed to be |
| equivalent result with a shutter speed of just 1 | | | | fine. However, there are three plastic tabs which |
| 60s, vastly extending options in low light | | | | basically hold the plastic barrel near the mount and |
| conditions. | | | | distance scale onto the rest of the lens. |
| Focusing is fast and sharp as with the $300 canon | | | | Capture your world with a 12.2 megapixel CMOS |
| lenses. I own two and pretty much use them | | | | sensor and the very latest Canon technologies. |
| more than most other lenses. Focus falloff is just | | | | The 12.2 megapixel CMOS sensor gives you |
| like a Sonnar, with the sharp central image and | | | | plenty of detail for poster-size prints and extra |
| lovely dissolve into nonfocus. Optimum aperture is | | | | flexibility when cropping. Canon has just made |
| f/4. Focus is achieved by front element extension. | | | | available Firmware Update 1.0.5 for the new |
| The ring-type USM motor dives the small front | | | | Canon 20D . This update fixes the lock-up |
| elements easily, resulting in extremely fast AF. | | | | problem that some users where experiencing. |
| Optically all three lenses are very similar. The two | | | | Canon is offering the lens kit at this discount so |
| non-IS lenses have identical optics but the IS lens | | | | that more customers can enjoy the benefit of a |
| has additional optical elements as part of the IS | | | | lens based image stabilizer system. |
| mechanism. Optical performance is noticeably | | | | Canon is recognized around the world for its |
| better than my cheap telephoto zoom. When | | | | innovations and advancements in the field of |
| used with the Canon EF 14X teleconverter, the | | | | optical technology. Nothing is more of a testament |
| maximum focal length becomes about 560mm, | | | | to this than the EOS EF Lenses. Canon's ring-type |
| and optical quality is still excellent. Optically it's | | | | USM gives silent but quick AF, along with full-time |
| almost on a par with the 300mm f/2.8L. In other | | | | manual focus. Dust- and moisture-resistant |
| words, this is as good as it gets. | | | | construction for a durable and sophisticated lens |
| Optical coatings are optimized for use with digital | | | | suitable for advanced amateur and professional |
| cameras. This lens focuses as close as 11 inches, | | | | photographers. |
| and offers both Canon's full-time manual focus | | | | |