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Old Nov 5, 2004, 7:25 AM   #1
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I am thinking of getting a canon 70-200L f2.8 IS but would like to add a canon/sigma/tamron 1.4x or 2x teleconverter to it. I am wondering, at 200mmx2x=400mm, will the IS work so that i can take handheld images?
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Old Nov 5, 2004, 8:39 AM   #2
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IS is completely independent of the TC (or a well-made extention tube.)

So it should help you hand-hold. It isn't the end-all-be-all, but it is certainly better than no IS at all. So you will get some shots that would otherwise have not been possible.

Eric
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Old Nov 14, 2004, 7:38 AM   #3
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I've got the 70-200 f2.8 IS USM lens and from all the "googling" that I've done, the 2x teleconverter should be avoided. Can't remember all the reasons but picture quality was the main one! I'm thinking of the 1.4 converter but can't afford it at the moment

Hope this helps,
Carl.
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Old Nov 14, 2004, 8:59 AM   #4
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CarlsPhotos is correct. The more powerful the TC, the worse the image quality (as a general rule.) This is because it magnifies any imperfections in the lens it is connected to. Use it with a cheap lens (which the 70-200 isn't) and the image quality will be really bad. Use it with a really good lens and the image quality won't be as bad... but it will still magnify what imperfections that are there. With the 70-200 it won't be horrible, but it won't be great either.

This is part of the reason why some of the really powerful telephoto lenses cost so much (400 2.8, 500 f4, 600 f4.) They can take a 1.4xTC with basically no loss in quality and the 2xTC is just a touch soft. Lenses that can do that are hard to make.

Lets not forget that they make the lens harder to keep steady as well. So that adds to the drop in image quality.

Eric
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Old Jan 1, 2005, 4:08 PM   #5
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Quality is also better if you use a lens with its matched TC's, using a generic OEM TC that fits on any lens will cost in image quality. This is why the Canon TC's can only be mated with some of their L lenses.
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Old Jan 1, 2005, 5:32 PM   #6
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The picture quality of a lens with a 2x TC depends on its aperture opening...
The image get better as the lens is stopped down

This picture with a 2x TC is quite usable IMO from a wide open 120-300 f/2.8 (ie 600mm @ f/5.6):




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Old Jan 4, 2005, 1:02 PM   #7
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All my functions wotk well with the 200 2.8 IS and a Canon 1.4 converter.

NHL: I am impressed with you photo with a 2x converter. Had been wondering if I should do that with my 200. Please advise me; is that quality the norm or 1 of many others that weren't up to par? That is a very good shot. Well done.
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Old Jan 5, 2005, 8:30 AM   #8
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IMO the worstcase would be @ wide open and up close... It only get better from there: ie acceptable when stop down a couple of f-stops and when the subject is further away where the increase in DOF also helps.

I have the Sigma combination, but there's plenty of examples on the Canon's as well: http://www.photosig.com/go/photos/browse?id=12999
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