The EF 17–40mm 4L USM lens is a
wide-angle lens made by
Canon Inc. The lens has an
EF mount to work with the
EOS line of cameras. Other than the front element, it is sealed against dust and water, and features a diaphragm which remains nearly circular from 4 to 8. It is one of the few Canon photo lenses that are
parfocal A parfocal lens is a lens (optics), lens that stays in Focus (optics), focus when magnification/focal length is changed. There is inevitably some amount of focus error, but too small to be considered significant.
Microscopy
Parfocal Objective (op ...
.
Audience
The 17–40mm is the least expensive of Canon's current wide-angle zooms for full-frame bodies, with the
EF 16–35mm 4L IS USM and
EF 11–24mm 4L USM being more expensive, and the
EF 16–35mm 2.8L USM being both faster and more expensive. Weighing 475 g and measuring 83.5 mm x 96.8 mm, it is a popular choice with many photographers because of its light and compact size.
A member of the
L-series, the 17–40mm is a good substitute for the 16–35mm 2.8 lens, which is heavier and costs approximately twice as much. Canon now sells an
image-stabilized 16–35mm 4 lens for about $300 more than the 17–40.
This lens is also a popular step up from the stock kit lens on many of Canon's EOS Digital family of cameras, the
EF-S 18–55mm 3.5–5.6, for those still wanting a wide angle lens. On a cropped sensor, it has
35 mm equivalent focal length
In photography, the 35 mm equivalent focal length is a measure that indicates the angle of view of a particular combination of a camera lens and film or sensor size. The term is popular because in the early years of digital photography, m ...
of 27–64mm. In this role, it is compared with the
EF-S 17–55mm lens, with which it can unofficially share lens hoods.
Companion lenses
This lens is often paired with an L series telephoto lens, such as the
EF 28–300mm 3.5–5.6 L USM or any of the
EF 70–200mm family (4L USM, 4L IS USM, 2.8L USM, 2.8L IS USM, 2.8L IS II USM).
Images
Image:Canon EF 17-40mm f4L USM front angled with hood.jpg, With the provided lens hood.
Image:Canon EF 17-40mm f4L USM lens mount.jpg, Weather-sealed lens mount with rear gelatin holder.
Image:Canon EF Nomenclature.jpg, Diagram of the lens, highlighting its different controls and features.
References
External links
Canon EF 17–40mm f/4L USM
Canon EF 17–40mm f/4L USM Lens Review
{{DEFAULTSORT:Canon EF 17-40mm lens
17-40mm
Canon L-Series lenses
Camera lenses introduced in 2003