Canon Extender EF II (1.4x) (6845A004C) Lens Converter

Pros: Light weight, relatively cost effective, works great with EF70-200mm lens, easy to carry
Cons: Physically looses one stop, slight image quality reduction, 40% additional magnification not very dramatic

When upgrading to Canon's 5D Mark II, the associated "full frame" sensor (35mm, un-cropped) converted all my lenses back to their "true" focal length and essentially gained in the wide angle while loosing some "reach". What's great in many ways certainly ...

Pros: A real "L" Professional Lens Extender with almost no degradation of the main lens's performance.
Cons: Why didn't I get one of these sooner? (Oh, yea, that's my fault... Never mind.)

Let’s say that you own a Canon “L” Professional telephoto lens and you also need a longer model, but it is completely beyond your reach, financially. That was my dilemma. My solution: the Canon EF Extender 1.4X II, coupled with the ...

Pros: Great accessory. Simple, compact, lightweight, effective.
Cons: Somewhat expensive for such a small accessory, slightly cumbersome to remove mid-shoot.

After receiving the 1.4x Extender, I shot about 600 shots at the San Diego Zoo and Wild Animal Park with the extender on a 70-200mm F2.8L (non-IS) Canon lens and a Canon 10D. I got the extender specifically for this type of shoot, as my previous visits ...

Pros: Solid construction, improves zoom w/ little loss of image quality or AF speed
Cons: PRICE - $300 ouch! Weight - it is heavy for its size

The Canon Extender EF 1.4X is a solid, hefty piece of equipment that adds significant zoom to (in my case) the Canon EF 70-200mm f/4.0L USM. The extender will cause you to lose an f stop but if your objective is to improve zoom capabilites then the tradeoff is worth it. I experienced little to no image degradation when using the extender. I also continued to enjoy the zippy zoom of the Canon EF 70-200mm f/4.0L USM with little loss of AF speed.

The nice thing about this extender is that you get a whole new zoom range without comprimising a lot of space in your bag.

I wouldn't recommend this piece for indoor photography as the loss of an f stop would hurt quite a bit, but for outdoor/nature/aviation photography it will give you the extra push if you need it.