Đánh giá lens canon 17-40l năm 2024

When used in the correct situations, ultra wide angle lenses (20mm or wider on full-frame cameras) can allow photographers to create very dramatic images, thanks to the extreme corner distortion and the stretch in perspective these lenses can create (these can also be considered negatives). Ultra wide angles are best used sparingly, but nevertheless tend to be a very important part of a professional photographer’s kit bag.

From what I can gather, quality ultra-wide angle lenses are typically very difficult to design and manufacture for SLR cameras, so tend to be rather pricey. With lenses such as the Canon EF 16-35mm f/2.8L USM II costing well over £1000, the purchase of an ultra-wide angle lens can be difficult to justify. At just over £550, the EF 17-40 f/4L has proved to be a very popular choice for many photographers. Continue reading to see why.

Build Quality and Ergonomics

As a member of Canon’s illustrious and revered line of ‘L’ series lenses, the Canon EF 17-40mm f/4L USM has superb build quality. The majority of the outer barrel is manufactured from a very high quality polycarbonate and is very durable.

The focus ring on this lens is superb. Size and placement are excellent, and turning the ring is smoother than any other lens I have ever used. Similarly, the zoom ring is great, although has slightly less resistance/damping than the focus ring, but this does allow the user to change focal lengths very quickly.

When zooming, the inner lens barrel moves internally, which is a very welcome feature, meaning that when coupled with a UV filter, this lens will be weather sealed thanks to the rear ass gasket and seals around the zoom and focus rings. Lens creep is seldom an issue with the 17-40.

On camera bodies such as the 5D, 6D, 7D or 1D series, this lens is very well balanced, and feels very comfortable when shooting. Weighing around 500g, having this lens mounted to any of the aforementioned bodies is no problem, even during prolonged periods and even with a battery grip attached.

The 17-40mm f/4L features a filter mount on the rear of the lens as well as the 77mm thread up front. This is useful when using multiple filters, as it helps to eliminate vignetting at the wider end of the lens.

Autofocus

The EF 17-40 features an Ultrasonic focus motor which is both quiet and very fast. At all focal lengths and in most lighting conditions, the 17-40 locks focus almost instantly with no hunting and is very accurate. Performance in AI-Servo mode is also very commendable.

As demonstrated below, the lens moves from infinity focus to close focus (0.28m) extremely quickly, faster than I can blink in fact. Amazing!

Image Quality

On a full-frame camera, the 17-40mm f/4L produces sharp results in the centre and mid frame at all focal lengths and apertures.

This lens struggles slightly with corner resolution, particularly when wide open at f/4. The issue is most pronounced at 17mm f/4, however the lens still produces images that are still more than acceptable at this setting. Stopping down to f/8 or smaller results in improved resolution, but colour fringing is still present.

The graphic below demonstrates corner sharpness at 17mm at f/4 and f/11. Both images are 100% crops from the bottom left corner of an image. Note the strong vignetting seen in the f/4 image and the slight colour shift from stopping down.

The 17-40mm controls flare very well and has very good contrast even in difficult lighting situations. This is important for landscape photographers looking to capture sunsets in the frame. The image below shows an example of such a scene. Note the attractive 14 point starburst this lens produces thanks to the 7 aperture blades.

At 17mm and f/4, there is strong vignetting in the corners. Stopping down to f/5.6 or f/8 will reduce vignetting. At 40mm vignetting is still apparent when shooting at f/4, but is less of an issue and again can be corrected by stopping down.

The 17-40mm zoom range is very useful for a wide range of applications on both full frame and APS-C (27-64mm f/6.3 equivalent). The comparison below shows the perspective difference that is apparent when using the same framing of the car. By shooting at 17mm up close, I was able to exaggerate the length of the bonnet. In contrast to this, shooting at 40mm from further back gave a more natural looking perspective, and less of the background is included because of the narrower angle of view.

The Canon EF 17-40mm f/4L USM has strong barrel distortion at 17mm and slight pincushion distortion at 40mm.

Bokeh is fair, but can be very harsh when objects are only slightly out of focus. Because of this lens’ relatively wide focal length (even 40mm) and moderate maximum aperture, achieving a defocused background can be a challenge. For me this is a no issue as this lens spends most of its time shooting deep depth of field scenes at f/11 to f/22.

Macro

The EF 17-40mm F/4 has a closest focusing distance of 0.28 metres. On APS-C at 40mm this close focusing distance is a welcome addition, meaning that this lens can be useful for certain still life macro applications.

Conclusion

Those looking for a full frame covering, high performance ultra wide angle lens with a versatile zoom range and professional build quality should definitely consider the Canon EF 17-40mm f/4L USM, regardless of their budget.

This lens is an excellent alternative to a 16-35mm f/2.8, particularly for landscape photographers, where a fast aperture is not necessary and narrow aperture performance is more important.

If you are using an APS-C camera but plan to upgrade to full frame in the future, this lens is still a very good option, as it offers a versatile 27-64mm focal range, and is 35mm compatible for when you do make the investment into a full frame camera, where this lens will take on a new lease of life.

Canon specs:

http://www.canon.co.uk/For_Home/Product_Finder/Cameras/EF_Lenses/Wide_zoom/EF_17-40mm_f4L_USM/

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All images and videos featured in this article are property of Lewis Gething Visuals and may not be used without prior consent from LG Visuals.