Canon 1.4X Extender EF III

SLRgear Review
October 3, 2011
by Andrew Alexander

The Canon 1.4x lens extender extends the focal length of a lens by 40%, making (for example) a 200mm lens function as a 280mm lens. The 1.4x series was introduced 1988, was updated in 2001 with the version II model, and again in 2010, the subject of this review.

Canon lens extenders were designed in the era of film, making them fully compatible with full-frame, APS-H and APS-C EOS digital cameras. The trade-off to the 40% extended range of the extender is the loss of one stop of light-gathering ability of the lens: accordingly, an ƒ/2.8 lens will operate as a ƒ/4 lens.

The 1.4x III Extender is available for around $480.

We'd like to thank LensRentals.com for their loan of this extender for our testing: to rent this lens, click here.

Sharpness
We used Canon's 200mm ƒ/2.8L II USM telephoto lens to test the 1.4x III Extender, comparing the sharpness of the lens with and without the extender attached. Without the extender, the lens shows very good results at ƒ/2.8, becoming almost tack-sharp at ƒ/4 through to ƒ/11.

With the Extender attached, sharpness is only slightly reduced. You'll never get tack-sharp results with the 1.4x III Extender attached, but decent performance is still obtained at ƒ/5.6, where things are more or less even across the frame.

It's worth noting that you can stop down to ƒ/45 with the Extender attached, but you won't want to, as images are distinctly soft at this setting.

Chromatic Aberration
There is a noticeable increase in chromatic aberration introduced by the 1.4x III Extender, at all apertures; you'll want to consult our sample images for more detail.

Shading (''Vignetting'')
Using the 1.4x III Extender alleviates corner shading noticed without the use of the extender, at the ƒ/2.8 setting, but that's only because the ƒ/2.8 aperture is no longer available. Technically, you're still shooting the lens at its f/2.8 aperture, but the extender is focused on the center region of the glass, where shading does not reach. At the widest setting of ƒ/4, the corners are only a 1/4 stop darker than the center.

Distortion
The 200mm ƒ/2.8L offers light barrel distortion in the corners and overall, very light pincushion distortion: adding the 1.4x III Extender to achieve 280mm introduces barrel distortion throughout the image (to a maximum of +0.25% barrel distortion in the corners).

Autofocus Operation
In our usage of the 1.4x III Extender, we did not really notice a significant impact on the autofocus performance of the 200mm ƒ/2.8L II USM lens, which is fast and snappy all on its own. However, Canon warns that there is an impact on autofocus performance with type II and III Extenders. Specifically, Canon suggests that AF drive speed is reduced by 50% when using the 1.4x Extender.

Macro
The 1.4x III Extender has some useful implications in macro work, offering an extra 40% magnification without sacrificing the minimum close-focusing distance; in the case of the 200mm ƒ/2.8L II USM, this results in 0.22x magnification instead of 0.16x magnification.

Build Quality and Handling
The Canon 1.4x III Extender is heavy for its size, at just under 8 ounces, suggesting a fair amount of metal in its construction. The finish of the lens is white, to match Canon's upper-tier L-class telephoto lenses, for which the lens is designed to be paired. The design of the lens is quite simple, 7 lens elements in 3 groups, and there is only one control surface on the extender: a switch to release an attached lens. Unlike previous version I and II extenders, the version III 2x extender cannot be combined with a 1.4x Extender to produce a significant increase in focal length. This is due to a redesign of the location of the lens elements, with a rear element that protrudes much further out.

Alternatives

As this is our first foray into teleconverter testing, we have no other tests to compare with, but here is a list of the current alternatives in the 1.4x category:

Canon 1.4X Extender EF II ~$320
The version III 1.4x Extender offers some slight improvement over the version II 1.4x Extender, with very slightly better results for sharpness, but much improved results for chromatic aberration. Distortion and shading results are about the same, though of course it will cost you a bit more for the version III model.

Sigma 1.4X EX DG APO ~$250

Tamron 1.4X SP AF PRO ~$225

Kenko 1.4X Teleplus PRO 300 DG AF ~$250

Conclusion
Again, we'd like to compare the 200mm ƒ/2.8 plus 1.4x Extender to the 300mm ƒ/4 to see what the quality difference might be, but we haven't yet tested that lens. In the meantime, we can certainly vouch for the optical quality of the 1.4x Extender III; you take a very slight hit on image sharpness, but not much else.

Product Photos

Sample Photos

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

Still Life shot

VFA target

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.