Canon EF 17-40mm f/4 USM L - Review / Test Report
Lens Reviews - Canon EOS (APS-C)

Special thanks to Chris Snelling for providing this lens!

Introduction

The Canon EF 17-40mm f/4 USM L, released in may 2003, is the latest of Canon's full frame ultra-wide zoom lenses. On APS-C DSLRs its field of view resembles a classic ~27-64mm standard zoom on full frame cameras so it is well suited for both formats but with different scopes. Thanks to its relatively affordable price combined with the promising L class (Luxury) designation the lens is fairly popular in the prosumer community.

With a weight of 475g and a size of 84x97mm the EF 17-40mm f/4 remains a quite compact and light-weight lens. The build quality of this lens is exceptional just as you would expect from a Canon L lens. No wobbling whatsoever and smooth controls - almost perfect. The lens is also designed to survive in harsh conditions with a sealing against dust and moisture. The outer length of the lens remains constant though the inner lens tube moves a little according to the zoom.
The petal-shaped hood is designed for full-frame (D)SLRs. On the downside this means it is a little small for being fully effective on APS-C DSLRs but using a polarizer with attached hood remains easily possible. If you prefer a deep, efficient lens hood (on APS-C DSLRs) you may consider to invest into a Canon EW-83D (originally meant for the EF 24mm f/1.4 USM L) which also fits the EF 17-40mm L (thanks to Henk den Bok for providing this info).

The optical construction is made of 12 elements in 9 groups, including one SUD (Super Ultra-low Dispersion) elements and three aspherical elements (one molded and two replica asphericals) so it's quite obvious that Canon has put quite some efforts into the design. The min. focus distance is 0.28m resulting is a max. object magnification of ~1:4 at 40mm. The lens features 7 circular aperture blades. The filter size is 77mm and you can use gel filters via a holder at the rear of the lens.

The lens has a ring-type USM drive based on a front-focusing system resulting in an extremely fast AF speed. Typical for ring-type USM lenses full-time manual focusing is always possible in one-shot AF mode.




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