Canon Extender EF 1.4x II - converter

...extender to go with my Canon EF 70-200 f4.0L IS lens. It extends the range to 280mm and increases the maximum aperture to 5.6. This means that autofocus on a 20D, 30D, 40D or 5D body will still function properly at any focal length.

Construction
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The construction is very solid (all metal) and matches the white EF-L lenses exactly so after a while you don't even notice it attached. You can easily remove ...
...teleconverter and if your lens has an o-ring seal then no dust or moisture can get into the join between the lens and teleconverter. It has an o-ring on the body side so maintains the sealing to the body. The only other downside is that its solid construction adds significant weight to what is already a pretty heavy piece of glass to begin with. But given the weight of these L series lenses, I'd rather have a teleconverter that was strong enough ... more

Overview
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I bought this extender to go with my Canon EF 70-200 f4.0L IS lens. It extends the range to 280mm and increases the maximum aperture to 5.6. This means that autofocus on a 20D, 30D, 40D or 5D body will still function properly at any focal length.

Construction
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The construction is very solid (all metal) and matches the white EF-L lenses exactly so after a while you don't even notice it attached. You can easily remove the lens combo from a body without accidentally detaching the teleconverter and if your lens has an o-ring seal then no dust or moisture can get into the join between the lens and teleconverter. It has an o-ring on the body side so maintains the sealing to the body. The only other downside is that its solid construction adds significant weight to what is already a pretty heavy piece of glass to begin with. But given the weight of these L series lenses, I'd rather have a teleconverter that was strong enough to take the weight without breaking or flexing than save a few grammes of weight.

Performance
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It's quite true that this teleconverter maintains the image quality of the 70-200 lens - I've not noticed any drop off in clarity and the combo still produces nice contrasty images without fringes or any other nasties that you might expect from adding a teleconverter. It also modifies the info sent to the camera so that the body "knows" that shots have been taken at 1.4 magification and so are recorded as such in the EXIF data. By itself, the adapter has next to no effect on battery life of the body.

Obviously the 1 stop drop in light is a drawback but it doesn't seem to affect AF performance or speed (at least on a 5D body) provided that you use a f4 or faster lens. Users of the 100-400 L might have a problem as the lens isn't a constant aperture type and so AF might not work at the long end. My 70-200 f4 has no trouble focussing with the adapter and by increasing the ISO by 1 stop (I use a minimum of 200), the combo performs much like a f4 lens at ISO 100.

You will however notice extremely shallow depth of field that can be either useful or troublesome, depending on what you are trying to achieve. Believe it or not a 280mm shallow focus lens is quite useful for landscape and portraits! I've taken some great closeups of my wife with the background totally blurred out when she was 5m away. In use, I've found I need to use a pretty fast ISO (800-1000) to get to the combination sweet spot (f11@1/300) otherwise the extra magnification can result in subject blur (even with IS) due to the shallow depth of field and slower shutter speeds that result from using the teleconverter.

Another fact to consider is that putting this teleconverter on any lens will increase its minimum focus distance, the 70-200 with it on now can't focus closer than about 5m!

Verdict
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A useful bit of kit, if somewhat expensive for what it is. 

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