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Canon Extender 2x II

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Intro   Specs   Performance   Compared   Usage   Recommendations   More

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Canon Extender 2x II

Canon EF Extender 2x II (Full-frame, 1.3x and and APS-C coverage, 9.4 oz./265g, about $250 used if you know How to Win at eBay). enlarge. I got mine at this link directly to them at eBay.

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October 2014   Canon Reviews   Canon Flash   Canon Lenses   All Reviews

Newest model: Canon EF Extender 2x III.

Canon Extender EF 1.4x II Review 16 October 2014


Introduction       top

Intro   Specs   Performance   Compared   Usage   Recommendations   More

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This Canon Extender 2x II is an ultra high performance teleconverter for use with Canon's high-performance telephoto lenses on all Canon EOS digital and 35mm cameras.

It multiplies your focal length by 2x and makes your effective aperture two stops less.

It makes your 70-200/2.8 into a 140-400mm f/5.6, or your 300mm f/2.8 into a 600mm f/5.6. It works with my 70-200/4 IS, making it a 140-400mm f/8.

It works with 70-200s and the 100-400, 135/2 and 180/3.5 macro, and otherwise is optimized for Canon's big white supertelephoto lenses. It wont work well or at all with f/5.6 zooms or normal 50mm, 85mm or 100mm lenses.

Most people say "converter" or "teleconverter" while Canon says "Extender." All use all these words and then all mean the same thing.

Canon Extender II Compatibility

Canon Extender II Compatibility Chart as of May 2008. Newer lenses should work, too. enlarge.

Be careful: since you lose two stops of light, your camera's autofocus may not be happy if your main lens is only f/4 or slower.


Specifications         top

Intro   Specs   Performance   Compared   Usage   Recommendations   More



Canon calls this the CANON Extender EF 2x II.

EF means "electronic focus." There is an autofocus motor inside the lenses — but not in this extender.


Optics       top

Canon Extender 2x II

Internal Construction, Canon Extender 2x II.

7 elements in 5 groups.



Diaphragm       top

Automatically calculates the actual working aperture and transmits that to the camera for exposure, viewfinder display and EXIF data.

For instance, with an f/2.8 lens, the maximum aperture is correctly reported as f/5.6 with the extender.


Size       top

Canon specifies 2.8" (71.8 mm) diameter by 2.26" (57.9 mm) long.


Weight       top

9.350 oz. (265.1 g).

10.257 oz. (290.8 g) including both caps.

11.310 oz. (320.7 g) including both caps and LP811 pouch.

Canon specifies 9.3 oz. (265 g).


Caps       top

It comes with a special front cap with extra clearance for the protruding front optics.

Standard EOS cap rear.


Case       top

Canon LP811 sack included.


Price, USA        top

2014 October: about $250 used if you know How to Win at eBay.


Performance       top

Intro   Specs   Performance   Compared   Usage   Recommendations   More

Overall    Focus   Bokeh   Coma   Distortion    Ergonomics    Falloff

Filters   Color Fringes   Mechanics   Sharpness    Sunstars


Overall     performance      top

The Canon Extender 2x II works great, but it only can do so much.

It really does give a much longer focal length, but with two stops less speed, while remaining pretty sharp and with very good AF performance.


Focus     performance      top

AF is slower, especially if it has to rack a long way in or out.

For relatively small changes in distance, it's very fast.


Lateral Color Fringes     performance      top

Every lens will work differently on every converter.

Used with my 300/2.8 which has no lateral color, there is slight yellow-green/violet lateral color with this extender, when used without a lens profile.

Most modern camera and lens combinations will have a lens profile available which will eliminate this.


Mechanics     performance      top

Canon Extender 2x II

Rear, Canon Extender 2x II, showing UV1201 date code. enlarge.


Front Lens Bumper



Barrel Exterior

Plastic front half, metal alloy rear half.



Seem like metal.








Serial Number

Engraved into bottom of barrel and filed with black paint.


Date Code

Printed on rear light baffle as shown above.

Mine has date code UV1201, meaning my sample was made in Canon's Utsunomiya plant in December 2007.


Rear Gasket (dust seal at mount)



Noises When Shaken

Minor clicking.



Made in Japan.

(pouch made in China.)


Sharpness     performance      top

The Canon Extender 2x II II is almost as sharp as the main lens. Every lens will perform differently on this extender.

Presuming you're using a top super tele (300/2.8, 400/2.8, 500/4, 600/4 and 800/5.6 specifically), the results should be excellent.

I haven't tried it with zooms.


Compared         top

Intro   Specs   Performance   Compared   Usage   Recommendations   More

There are three versions: the original (1987-2001), this -II version (2001-2010), and the current -III version (2010-).

Each newer version has slightly different optics. Ultimate optical quality depends more on your main lens than the converter. Each newer version shows only slight, if any, improvement over an earlier version.

The real differences are sales features, like dust gaskets or fingerprint-resistant coatings.

This -II version adds a rear dust seal.

The -III version adds fluorine optical coatings to resist fingerprints. It has different electronics that eliminate compatibility with older 35mm EOS cameras.


Usage       top

Intro   Specs   Performance   Compared   Usage   Recommendations   More



You can use this 2x extender along with a 1.4x extender for a total of a 2.8x increase in effective focal length, with a loss of three stops of light.

If you do this, put this 2x extender on the lens and the 1.4x extender on the camera. This way the extended front element of the 1.4x will poke into the rear recess of this 2x extender.

For some unknown reason, when I stack both this 1.4x II and 2x II extenders, the camera reads two, not three stops, aperture change, and only 2x, not 2.8x, focal length increase. Watch your EXIF data, it seems to ignore the 1.4x converter when used at the same time as a 2x converter.

Use either an original version or this -II version 2x extender.

The newest version Canon Extender 2x III has its rear element too far back so that we can't stack a 1.4x with it.

I have not tried stacking two 2x extenders.

When stacking the 1.4x II and this 2x II extenders, AF sometimes will try to hunt if atmospheric heat shimmer is making the target appear to float in and out.

With my 300mm f/2.8, I get some green/magenta lateral color and it's not quite as sharp and not quite as fast at AF (althoguh AF is still surpricinyl fast if there's not that far to go), but honestly if you need the range and have an f/2.8 lens, go for it.


Recommendations       top

Intro   Specs   Performance   Compared   Usage   Recommendations   More

2x extenders are great if you ocasionally need a much longer lens. A 300mm f/2.8 converted into a 600mm f/5.6 is never as nice as having a dedicated 600/4, but if you need both lenses at the same time and your assitant is on vacation, it's much easier to carry this extender than the extra 600/4.

There is very little difference between Canon's different versions of 2x extender. I wouldn't go out of my way to get the -III if you already have this -II, and I wouldn't go out of my way to get this -II if I already had the original version.

See Is It Worth It for more on upgrades. If you're using this on a $10,000 lens every day, by all means get the -III, but for more casual use, there is negligible difference.


More Information         top

Intro   Specs   Performance   Compared   Usage   Recommendations   More

Canon Camera Museum.


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15 October 2014