Need some extra reach with your camera?
An extender is always an option to extend your lens' zooming capabilities without spending thousands of dollars for a larger lens.
Extenders magnify focal lengths. For instance, a 200mm lens with a 1.4x extender attached becomes a 280mm lens because 200 multiplied by 1.4 is 280.
I mention that particular focal length because that's what I've been testing for the past few days. A good friend of mine graciously let me borrow his Canon 1.4x iii Extender. The iii means it's the third version of this extender released by Canon.
How did they get to a third version?
Well, the explanation is fairly simple — extenders are good in that they magnify your focal length, allowing for more reach with a longer lens, but extenders also decrease image quality. The extenders Canon released before the third iteration were horrific when it came to image quality. Finer details were lost in photos and it was a high price to pay just for a bit of extra reach.
Version three isn't too bad from what I'm seeing, and it's really nice to have the extra 80mm when going out to shoot wildlife.
As a rule, it's always better to purchase lenses with longer focal lengths (300mm, 400mm, to name a few) built into the lens. The lens was made for those focal lengths, and adding an extender does increase the reach of those lenses ... but at an image quality cost.
An additional cost is the actual expense of the extender. The Canon 1.4x iii extender costs a whopping $500 new.
Now, that is fairly cheap compared to going out and buying a lens (depending on the lens purchased), but it's also hard to justify the cost of such a small device when it decreases image quality so significantly. At least for me anyway.
Another downside to using an extender is that there is a loss of light. You're adding more glass elements in between your lens and camera body by attaching an extender to it, and by doing so you lose a couple stops of light because the opening through which light travels through your lens (aperture) has that much more distance to travel. So, effectively an f/2.8 lens with the 1.4x extender attached to it becomes an f/4 lens.
That's not such a big deal to me because what I need the extra reach for is wildlife photography, and I mostly go out to shoot wildlife during the brighter daytime hours.
Extenders only work with certain lenses as well. For instance, you’ll never see an extender on a wide angle lens such as a 16mm lens. It would be redundant to try that and it would also break the lens. Extenders are meant for telephoto lenses only.
Image stabilization in a lens also can help limit the drawback of the loss of light. Image stabilization is a really cool feature in a lens because it limits camera shake caused by handholding a camera. When your aperture is at a higher value (due to the extender), you'll need to compensate for the loss of light with a slower shutter speed and, thanks to image stabilizer technology, slower shutter speeds are not as much of a problem anymore.
So my overall take on this device? I like it a lot. The image quality decrease isn't huge and the loss of light also isn't a huge deal to me. Will I invest in one? Maybe someday, but for now I'm going to keep saving up for a lens that has longer focal lengths natively built in.
What can I say? I'm a sucker for pristine image quality.
For the consumer that doesn’t want to invest in a several thousand dollar super telephoto lens, an extender is a great alternative.