| Field-test of the Canon Extender
EF 2x. Canon offers two types of tele-extenders for use with some of its L-series zooms as well as telephoto lenses having focal lengths of 135mm and longer. They are the Extender EF 1.4x and EF 2x. The former increases the effective focal length by a factor of 1.4x with a one-stop loss of the lens' effective aperture while the latter multiplies it two times and two stops reduction. For example, when the EF 200mm f/2.8L II USM lens is fitted with the EF 1.4x, its focal length will become a 280mm f/4 telephoto instead. On the EF 200mm f/1.8L USM lens, its effective focal length will become a 280mm f/3.5 instead. If the EF 2x is attached on either lens, the effective focal lengths will be a 400mm f/5.6 for the former and a 400mm f/6.3 (on EOS-3 and EOS-1 series cameras) for the latter. These extenders will also work on three L-series zoom lenses: the EF 100-400mm f/4.5-5.6L IS USM, EF 70-200mm f/4L USM and the EF 70-200mm f/2.8L USM. Autofocus is possible when the 1.4x extender is used on the two 70-200mm zooms but not on the EF 100-400 IS lens, unless you are using either the EOS-3 or the pro EOS-1v. Autofocus is not possible on any EOS camera when the EF 2x is attached to the EF 100-400mm IS zoom lens. In this issue, the focus is entirely on the Extender EF 2x while the 1.4x version will be featured in the near future. Weighing only 240 grams, this 2x Extender is extremely compact and light, making it very easy to use even with super telephoto lenses like the EF 200mm f/1.8L USM, EF 300mm f/2.8L USM or the new EF 300mm f/2.8L IS USM - handheld, despite the increase in the effective focal lengths.
An advantage of using this Extender with a prime optics is: the closest focusing distance of the lens in use is not affected, allowing the photographer a further boost in increased magnification of the subject in addition to the two times multiplying factor. Attaching this high-performance Extender to a 135mm and lens or to the EF 70-200mm f/4L/2.8L USM zooms, will boost the focal length by 2 times. With seven elements in five lens groups, it preserves the prime lens' image quality since it is designed to give the best performance with any of the EF lenses that can accept both the 1.4x and 2x Extenders. When it is attached to the EF 180mm f/3.5L USM Macro lens, a 2:1 magnification of the subject is possible. However, AF is disengaged even when the EOS-3 or EOS-1v is used with this EF 180mm Macro Lens. << Back to Main . 1 . 2 . 3 . 4 . |
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