Canon 2X Teleconverter EF

I wanted to revise some impressions I noted in my initial review about this 2xTC. I first felt that results were mediocre when used with the Canon f4L. But I've since noticed that if stopped down to f11 (this would be f5.6 without the TC) then sharpness and purple fringing get MUCH better. So in bright sunlight, this lens+TC combination can deliver quality pictures after all. I also complained about how the Canon TC disables autofocus with my lens, whereas the cheaper models don't. I've since come to realize this is a blessing in disguise. With an effective max f8, autofocus is too erratic to depend on, and it SHOULD be disabled, to prevent one from trying to use it. Finally, I had originally complained that optically the Canon converter is no better than the cheaper brands. I still find this largely true, with the exception that some cheaper 2x converters "only" magnify about 1.8x or so, whereas the Canon is exactly 2x. In the end, I still think Canon's price is too high, but the factors lead me to upwardly revise my rating.

Disables autofocus (seems like a weakness, but actually makes sense).

I tried this with a Canon 300f4L. Results were mediocre, and not any better than a cheap Quantaray 2xTC with the same lens. In fact, autofocus stopped working with the Canon TC, whereas it worked great with the cheap-o Quantaray. I think this is because the Canon TC correctly recalculates the max aperture from f4 to f8, signaling the camera to disable autofocus, whereas the "dumb" Quantaray lets camera think the lens is still f4. Aside from loss of autofocus, my main problems were loss of sharpness and purple fringing. I had to use lots of unsharp masking to make pictures taken with the 300f4L + TC combo look decent. This is probably a limitation of the base lens, not the TC. I presume that a better lens would have given better results, but this is already an "L" lens, for crying out loud, and is incredibly sharp compared to my non-L lenses. My 300mm lens has a small amount of purple fringing wide open, which became intolerably gross with 2x magnification. I'm convinced that the 2xTC magnifies the fringing MORE than the image itself. I didn't think the TC was worth the high price. It wasn't any better than even the cheapest 2xTC from Quantaray, and was arguably worse because of the loss of autofocus. If you really want this 2x TC, I suggest trying the cheap versions first. You might be surprised. Image quality is MUCH more dependent on the quality of the base lens than of the TC you attach to it.

Easier to sell because of the Canon name.

Not detectably better than cheaper brands with my lens (Canon 300f4L).

Quantaray 2xTC Canon 1.4xTC Tamron 1.4xTC Promaster 1.7xTC Tamron 2xTC (SP and non-SP)

Like the 1.4x converter this is expensive but works really well with Canon 'L' lenses... or at least it does with the 70-200L I have. I haven't had it long but have taken alot of shots and certainly enough to be well impressed with the quality for what it is. In terms of it's effect on the autofocus it will hunt a bit depending on light conditions and you loose a bit of speed but I don't think it is too bad at all. Not quite as good as the 1.4x but still impressive.

Image quality Build

Quite long Price Can't be used on many lenses

Canon 1.4x converter

Not used.

I use this high performance extender with my 70-200L f/2.8 with very good results. The image quality is preserved. It increases the focal length by 2 times and decreases the f-stop by 2 sops. The lens becomes a 140-400L f/5.6. AF is possible with my EOS 3 and my EOS 50e. I don''t regret each pound...

* AF performs very fast with my combo (70-200L f/2.8) when used in good light conditions. * The money spent to get a super telephoto lens (400mm f/5.6) keeping the versatility of the zoom. * Perfect for telephoto "L" lenses.

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Brilliant 2x extender. I use it with the 300 f2.8L, which makes it a 600 f5.6. Which is nice!! Af speed does suffer a little - but as I shoot Formula 1 cars, I would notice alot. But for other subjects it would be fine. Picture quality is extremely good - even when the slides are viewed under an 8x loupe. In short...it makes the 300 a great 600 f5.6 (and quite alot cheaper than a 600 f4!!!)

Picture quality. Good Af speed (when used in sunny conditions) Build and look. Price at the moment.

AF suffers in poor lighting conditions.

Canon 1.4x Sigma 1.4x

never needed