Rudy Winston
Rudy Winston

Rudy Winston has over 14 years experience with Canon USA's Pro Products team, and has been responsible during that time for training Canon's staff on new products, creating presentations for customers and dealers, numerous writing projects, and providing technical assistance to professional and amateur photographers.

The Canon EF 200-400mm f/4L IS Extender 1.4x lens and tele extenders

May 23, 2013

Canon’s new EF 200–400mm f/4L IS Extender 1.4x lens is the industry’s first AF zoom lens for interchangeable lens SLRs that incorporates a built-in tele extender. This technology isn’t brand-new — it’s actually been seen in some top-of-the-line broadcast TV lenses, such as some of the box-shape TV camera lenses you see at major sporting events. But it’s the first application of this technology for digital SLR camera owners. The potential advantages are numerous, and some may seem obvious. In this article, we’ll attempt to shed light on how the 200–400mm lens is used, as well as what impact it has if a user is thinking about adding a traditional, external 1.4x or 2x tele extender to this new lens.

The built-in 1.4x extender:

The EF 200–400mm f/4L IS Extender 1.4x lens is already noteworthy for its sophisticated 25-element optical design, which includes a large-diameter Fluorite element in the front lens group, and a total of four UD (Ultra-low Dispersion) glass elements. The built-in 1.4x tele extender is a separate set of lens elements, which can be flipped into position or removed from the optical path altogether, via a two-position switch on the left side of the lens.

This built-in 1.4x extender is an eight-element design, and is optically and completely different from the standard accessory EF 1.4x III extender. The extender effectively changes the lens from a 200–400mm f/4 into a 280–560mm f/5.6 lens. Optically dedicated to this lens, it promises to deliver maximum optical performance when it’s used. When not being used, the added 1.4x extender elements are physically moved aside and housed in a relatively small rounded area that protrudes slightly on the left side of the lens barrel (technically savvy readers will note that with the eight-element extender in place, this lens is a 33-element design — by far the most complex optical design in the EOS lens system to date).

A simple flick up or down on the large extender switch lever on the side of the lens moves the extender into place, or removes it and reverts the lens back to 200–400mm f/4 operation. Considering that there are eight elements in the extender section, the movement of this lever is super-smooth and precise — most users will find it can be achieved with one finger. A sliding lock switch forward of the lever locks the lever in place, in either position.

Shooting with the built-in 1.4x extender:

The beauty of the built-in extender design is that it can be used or removed quicker than installing or removing a typical accessory tele extender. For any user, especially in outdoor conditions, this minimizes the risk of dust, rain or snow impacting the lens or camera body during extender changes. And especially for any user working with the lens on a monopod, it greatly reduces the risk of dropping an extender, camera body or lens when trying to quickly make this change. It’s a far quicker operation — sliding the lock switch and moving the lever is something that can be achieved within a few seconds.

The 400mm maximum focal length of the lens alone is often marginal for nature, wildlife and motorsports enthusiasts — a reason why the 500mm f/4 design has been so important to working pros and dedicated enthusiasts in these fields. For these shooters, the ability to instantly convert the lens into a 560mm f/5.6 makes this new lens a potential game changer. By simply moving the built-in 1.4x extender into place, tighter compositions from distant locations (like on a sports field, court, track or wildlife) can be achieved. With the improved high-ISO performance of recent digital SLRs, the f/5.6 maximum aperture is less of an obstacle than it might have been in the past. And when the light gets low or users want to shoot at wider focal lengths, it’s a one-finger operation to remove the extender and revert to 200–400mm operation.

Image Stabilization is an important tool in many telephoto applications and are all the more so when tele extenders are in use. The EF 200–400mm’s optical Image Stabilization provides correction equivalent to using shutter speeds up to four stops faster, making monopod operation an entirely practical option for many users even during overcast or dimly-lit conditions. When the built-in tele extender is used, the four-stop correction effectively means (using the old 1/focal length of the lens “rule of thumb”) that sharp shots of stationary objects can be taken at shutter speeds approaching 1/30 of a second for many users. Every photographer and every situation is different, but the Image Stabilizer broadens the range of situations that this lens can be effectively used in.


As is the case with conventional 1.4x and 2x tele extenders, the built-in extender in the EF 200–400mm lens does not change the lens’ 6.6 feet (2m) minimum focus distance. This makes it even more versatile for certain types of nature shooting, especially for wildlife shooters who photograph birds and other small creatures. With the built-in 1.4x extender in place and the lens zoomed to its maximum telephoto position (560mm equivalent), at the minimum focus distance it’s possible to fill the frame with a subject roughly the size of a U.S. dollar bill using a full-frame camera body. Maximum close-up magnification in this configuration is 0.21x, approximately a 1:5 reproduction ratio. It’s true this hardly qualifies as a macro lens, but this close focusing capability will be useful to some location shooters. And it’s the inclusion of the built-in 1.4x extender that completes the effectiveness of this lens for shooting small subjects from close distances.

Can I use this lens with Canon tele extenders I already own?

The answer is a definite “yes.” The EF 200–400mm f/4L IS Extender 1.4x can be used with conventional accessory Canon EF tele extenders. Either the accessory 1.4x or 2x extender can be attached and used with this lens. The lens’ built-in 1.4x extender can be combined with either of the accessory extenders, further increasing the lens’ long-range capability without compromises in size, weight or minimum focus distance.

With the built-in 1.4x extender in place, here’s what you have when adding an accessory Canon EF tele extender:

  • With EF 1.4x: 392–784mm f/8 equivalent
  • With EF 2x: 560–1120mm f/11 equivalent

And, of course, an accessory 1.4x or 2x EF extender can be used without the built-in 1.4x extender applied as well.

Simply stated, combining the built-in 1.4x extender along with an accessory EF 1.4x unit transforms this lens into roughly a 400–800mm lens with an f/8 maximum aperture that’s still very usable in many daylight conditions and allows AF at the center AF point with popular cameras like the EOS 5D Mark III.

While any version of Canon’s EF extenders can be used (original 1.4x or 2x, Version II or Version III) with the original and Version II extenders, it’s possible with some EOS bodies that AF may require micro-adjustment for optimum focus precision, if the camera offers micro-adjust capability. This should not be an issue with the newer Version III 1.4x or 2x Canon EF tele extenders. When possible, Canon recommends using Version III tele extenders in conjunction with the EF 200–400mm f/4L IS Extender 1.4x lens.

AF compatibility when built-in and external extender are combined:

Regardless of the version of a Canon accessory tele extender, the basic rules of AF compatibility continue to apply. The built-in extender of the EF 200–400mm f/4L IS lens does not change whether or not AF will continue to work with specific EOS camera bodies.

  • Nearly all Canon EOS cameras made to date require a lens, or lens plus extender combination, with a maximum aperture f/5.6 or faster in order to be able to autofocus. When the camera detects that the maximum possible aperture is slower than f/5.6, it shuts down AF.

    Full AF is possible with any EOS SLR produced to date with the EF 200–400mm lens, with or without its built-in extender in place.

  • EOS 5D Mark III (firmware version 1.2.1 or higher) and EOS-1D X (firmware v. 1.1.1 or higher): AF is possible with a compatible Canon lens plus extender combination having a maximum aperture of f/8 or faster. AF will only work at the center AF point (and four surrounding points if AF Expansion is active) when a maximum aperture slower than f/5.6 is detected.

    AF is possible at the center AF point when both the built-in 1.4x extender of the 200–400mm lens and an accessory EF 1.4x extender are combined.

  • Previous high-end EOS cameras having the 45-point AF system (all previous versions of EOS-1D, EOS-1Ds and 35mm film cameras like the EOS-1v and EOS-3): AF is possible at the center AF point only, with maximum apertures down to f/8. When maximum apertures are f/5.6 or faster, all AF points are available for AF.

    Same as 5D III and 1D X — AF is possible at the center AF point with 45-point AF systems when the 200–400mm lens is used with the combination of built-in 1.4x and external 1.4x extenders.

To clarify some confusion that’s led to misinformation on Internet forums and so on, this has nothing to do with the aperture you want to shoot a picture at. The AF system is only concerned with the maximum aperture of the optics attached to the camera body. As long as the maximum aperture is within the limits mentioned above, you can freely shoot pictures at any aperture you like, down to minimum apertures such as f/22 or f/32.

Other notes about extender operation:
  1. With any EOS bodies introduced prior to EOS-1D X, EOS-5D Mark III, EOS 6D and EOS Rebel T4i (650D): Switching the lens’ extender lever in either direction should only be performed when Live View or Video mode is off (LCD monitor not active) and when camera is inactive (not when pressing shutter button half-way, Image Stabilization active, writing to memory card and so on).
  2. Moving the extender lever on the lens is possible during LCD monitor operation with those SLR models listed above or subsequently introduced EOS cameras. Users should still make sure that the camera is momentarily inactive (not writing to memory card, etc.) before moving the lever.
  3. For technical reasons, with older EOS 35mm film cameras (original EOS-1, EOS A2/A2E and EOS 5, EOS RT, etc.), Image Stabilization will not function if AF has been shut down by the camera. Accordingly, if the EF 200–400mm lens is used with its built-in extender and an accessory extender, both AF and IS will not function. IS and AF will work normally with these cameras if the lens alone, or lens plus its built-in 1.4x extender, are used.

The new EF 200–400mm f/4 lens is one of the most anticipated lenses in recent memory, and part of the reason why is its unique built-in tele extender. Far from a mere convenience, this new feature makes it possible to transform this lens into an even longer lens when conditions allow and to freely switch in and out of tele extender operation as conditions dictate.

Perhaps even more so than with conventional accessory tele extenders, this new lens will encourage some users to almost consider the lens to be a 280–560mm f/5.6, that can be converted into a faster f/4 lens in lower light conditions. And the fact that it can continue to be used with existing 1.4x or 2x extenders further cements its versatility and opens up new shooting possibilities.

The use of tele extenders, highlighted by the built-in 1.4x in this lens, make the EF 200–400mm f/4L IS Extender 1.4x lens a virtual Swiss Army knife to different types of outdoor location shooters and photojournalists. It presents a pleasant but difficult choice for photographers who may be comparing this lens to traditional fixed focal length Canon super-telephoto lenses.

The CDLC contributors are compensated spokespersons and actual users of the Canon products that they promote.

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