Canon Teleconverter 1.4

[Paul Tomlinson]

I am looking at buying a teleconverter and i have heard that canon 1.4 is better then the 2* teleconverter, is this so.

Paul Tomo

 

[CT]

Teleconverters are a cheap solution to more reach when compared to the cost of buying a longer lens. A TC is basically just a magnifying glass stuck behind a lens to give a larger main subject image on the sensor/film. Any inherent poor qualities in the lens are just made far worse by adding a TC, so sticking a TC behind a poor lens isn't a good idea. Zoom lenses are also compromised in comparison to a prime lens, so generally speaking converters behind a zoom lens aren't a good idea, but if you must, then make sure it's a quality zoom, and I wouldn't recommend using a 2X TC, but a 1.4X TC could get you more than acceptable results behind a quality zoom.

You should really just try to use converters behind a good prime lens. I mainly use a 1.4X TC behind my 500mm f4L and there's little if any discernable loss in IQ. I also use the 2X TC with the same lens on occasion, and it produces good results though not as good as the 1.4X TC.

Other things to note are that the 1.4X TC loses you one whole stop, while a 2X TC will lose you 2 stops. My 500mm f4 becomes effectively an f8 lens with a 2X converter and that's the maximum aperture, so you need pretty good light to keep the shutter speed reasonable.

 

[adsayer]

CT: how does the AF fair with the 500 F/4L with the 2x TC on it?

I was under the impression the xxD range couldn't AF beyond f/5.6?

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Paul: from my experience I've seen no difference in IQ between the Canon 1.4x and the Kenko DG Pro 300 1.4x - the kenko is cheaper and fits more lenses which is nice
However I've used the Canon 2x on a 70-200 F/2.8 IS and th IQ took a major hit which was disappointed, but ultimately to be expected.


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[CT]

CT: how does the AF fair with the 500 F/4L with the 2x TC on it?

I was under the impression the xxD range couldn't AF beyond f/5.6?

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You're quite right Ads, the Canon XXD range only retain AF with a 2XTC if the effective aperture with the converter fitted is f5.6 or larger. In short, I lose AF with the 500mm on my 40D with a 2X TC. My 1DMK2n, which I've now sold, did retain AF with a 2X TC on the 500mm F4.

However, the reason I sold the 1DMK2n, is that my 20D was producing the same size main subject images with a 1.4X TC as the 1DMK2n with a 2X TC. This was comparing the size of that Robin (say) from each body in the outputted 1:1 file. (The 20D and the 1DMK2n both produce the same 1:1 full size image) In fact, the 20D with the 1.4X TC was producing slightly larger images, but not by enough to be really significant.

The situation will be exactly the same if you carried out the same tests using a 40D and a 1DMK3 as both cameras produce the same full size file. So ...while the 40D doesn't AF with the 2X TC, I don't find it any loss at all, and I only lose one stop with the 1.4 TC whereas I'd lose 2 whole stops with a 2X TC for the same size image, (on a 1DMK3) and inevitably, a more degraded image.

Obviously, for ultimate reach I'd use a 2X TC on the 40D but lose AF .