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The image sensor in the EOS 1D and EOS D30 is smaller than a 35mm film frame. This means that the angle-of-view of an attached lens is narrower for the digital cameras than for film models. The result is that a lens attached to digital cameras appears to have a longer focal length than the same lens attached to a film camera.

Most of the time, this is not too much of a problem. You can use a shorter focal length lens on the digital camera to overcome the effect. Unless, of course, you are already using an ultra-wide-angle lens.

It is with this in mind that Canon has introduced the EF 16-35mm f2.8L USM lens as a replacement for the EF 17-35mm lens. The range may only have increased by 1mm, but at the wide-angle end this is much more significant than a 1mm increase at, say, 300mm.

However, this is not just a lens for EOS digital cameras. It offers benefits for all EOS models:

• the first EF lens with three types of aspherical elements ­ ground, replicated and glass-molded ­ giving higher image quality than the EF 17-35mm lens;
  

• two UD elements to provide effective correction for the chromatic aberrations which are a particular problem with wide-angle lenses;
  

• increased resistance to dust particles and water droplets, complementing the water and dust resistance of the EOS 1V;
  

• inner focusing and ring USM for silent, high-speed autofocus (AF) operation (significantly faster than wit the EF 17-35mm lens);
  

• circular diaphragm for better background blur ('bokeh')
  

• minimum focusing distance of 0.28mm at all focal lengths.

The lens is compatible with Extension Tubes, but not with Extenders. Close-up lenses 500 or 500D can be used (the filter thread is 77mm). There is also a rear drop-in filter slot.

Size and weight are 83.5 x 102.7mm and 600g (7mm longer and 55g heavier than the EF 17-35mm lens).

The 16-35mm f2.8L USM lens comes complete with EW-83E lens hood,  LP1319 soft pouch and lens cap E-77U. Should be available early November 2001.

Specification

Focal length: 16-35mm

Aperture range: f2.8 to f22

Aperture blades: 7

Construction: 14 elements in 10 groups (including three aspherical elements); inner focusing

Filter mount: 77mm

Minimum focus: 0.28 metres

AF drive: ring USM

Manual focusing: enabled with focus mode switch and focusing ring

Extenders: not compatible

Extension tubes: compatible with EF12/EF25

Close-up lenses: CU500/500D