Monday, November 24, 2008

Teleconverter Shootout - Tamron vs Canon

Yesterday I posted a review of the Tamron 1.4X and 2.0X teleconverters. As I mentioned there, I was quite happy with the test results, but I also wanted to compare them to the Canon teleconverters to make sure there wasn't a significant difference between the brands (and if there was, I could exchange them before my return period ended). Well, I got in touch with my friend Wayne Fisk, who happened to own both of the Canon teleconverters, and I was able to borrow them for a few hours to do a quick comparison.

Physical design

As it turns out, the biggest difference between the Canon and Tamron teleconverters is in physical design. When you first look at them side by side, you will notice the Canon's are considerably larger, with the 2.0X showing the biggest size difference. When you pick them up, the Canon's are also heavier than the Tamrons, but the biggest surprise is that the 1.4X models have the biggest difference, with the Canon being almost twice as heavy as the Tamron. Measuring both teleconverters together, the Canon teleconverters combined are about 1/3 lbs heavier and about an inch longer.

When you pull of the end caps, you will see more of a difference. While the back of the 1.4X teleconverters are nearly identical, the front sides are quite different. The Tamron had the front lens element recessed, while the Canon sticks out enough to protrude into the lens it is attached to. This is why the Canon teleconverters can only be used on select Canon L series lenses, while the Tamrons will work on almost any lens.

This also becomes a concern when trying to connect both teleconverters together for a combined 2.8X magnification. With the original Canon teleconverters, you needed to add an extension tube between the 2 to get them to connect. With the redesigned II series teleconverters, the 2.0X now has an indentation in the back to accept the protrusion from the 1.4X. This means you can only use the Canons together with the 2.0X closes to the lens, while the Tamrons will let you use either arrangement. Optically, it shouldn't make a difference. However, if you wish to use a lens that is slower than f/2.8, then you cannot use autofocus with the arrangement the Canons demand. As I stated in yesterday's review, even if you can trick the camera into autofocusing with more than the 1.4X, it doesn't seem to do much good as it has great difficulty (to put it mildly) achieving autofocus, so this doesn't seem to be an issue. However, just like the Tamrons, the new Live View contrast based focusing works perfectly with any teleconverter combination.

Back of both 1.4X teleconverters

Front of both 2.0X teleconverters (the 1.4Xs look the same as these)

Back of both 2.0X teleconverters

The one other significant difference between the Canon and Tamron teleconverters isn't so easy to see, but if you look at the above photo carefully, you can see that on the Canon there is a thin black line between the metal mount and the white shell. This is the black rubber weather seal, which is intended to help keep water from leaking in in wet conditions. The Tamron teleconverters lack any sort of seal. However, it's worth noting that unless you have the Canon L series lenses and the higher end camera bodies, you probably don't have any weather sealing on the lens and body either.

Image Quality

I ran each combination of teleconverters from each brand through a few different tests. The first test was done with the camera at a fixed distance from my target. In the second and third test images, I varied the distance from the target depending on the teleconverters used, in order to make the target appear the same size in each photo, no matter what the magnification.

In the end, I saw no significant differences between the Canon and Tamron teleconverters in terms of sharpness or contrast. In some photos, one brand will look better than the other, in others the other brand wins, but in every case you need to look very carefully to decide. In fact, even when I thought one brand looked better, often coming back to the result 30 minutes later would give me the opposite impression. In short, it is extremely difficult to see the difference between the 2 brands, and I'm often not sure there even is a difference. As far as I'm concerned, they are nearly functionally identical.

Click any of the 3 images below to see the full size comparison images.


This quick test confirmed reports I had read that these 2 brands of teleconverters were almost identical. I'm completely satisfied that there is no real difference between the image quality of the 2 brands, and thus I'll be keeping the Tamrons. If you have a need for the weather sealing, then the Canon might be worth considering. For most users, though, I'd say the Tamron teleconverters represent a much better bargain, and thus I'd highly recommend them.

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