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Old Nov 9, 2003, 10:33 PM   #1
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Default Is this possible to have (2) teleconverters??

I was wondering if it is possbile to attach (2) teleconverters on to the Canon EOS Rebel or any camera infact? I have a 2x teleconverter, but I saw on a submission for a photo that the person had these specs for the camera:

Taken with my Canon 10D and: Canon 100-400mm IS/USM (@ 400); Canon 1.4x teleconverter; Kenko 1.4x teleconverter; For a combined focal length of: 1254mm (25x).

So with that specs, is it truely possible? If so I can attach another 2x converter to the current one that I have, with lets say my 70-300mm ??
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Old Nov 10, 2003, 12:28 AM   #2
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Yes, it is certainly possible. But there are several problems:

1) You'll loose 4 f-stops worth of light. (2 for each 2x TC.) You had better be taking the picture in bright daylight, or it won't work. It's a matter of physics, it can't be worked around.

2) You'll loose AF. Manual focus isn't a bad thing, but its hard when you're maximum aperture is f11 or so.

3) With a 1200mm lens (then x 1.6 because of the Rebel's sensor size) the camera will be very hard to hold steady. You'll need an amazingly good tripod and long lens technique. Can it be done? Probably. Will it look good? Probably not. Will it have motion blur? Almost certainly.

4) You need really good optics. The TCs magnify any flaws in the lens (and the second TC magnifies any flaws in the lens and the first TC!) I've seen 2 2xTCs (both Canons) used on a 600mm f4 (a lens with amazingly good optics.) The picture looked... ok. It was nice to use to figure out what the bird was way out on the ocean, but you wouldn't even consider printing it out.

It should also be noted that the Canon TCs don't work on every lens. The Kenko's are better, and will work with most (if not all) of Canon's lenses. It's a physical limitation that can't be worked around (part of the Canon TC protrudes outwards towards the lens. Lenses with close rear elements will hit the protrusion.)

So you might be able to do it, but it will be very dark and very hard to get a sharp picture. If you could borrow the extra TC, you could try it. But I would put down cash just to test the theory, the 2x TC is expensive for such a test.

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Old Nov 10, 2003, 10:34 AM   #3
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Default Thanks!

Yeah I didn't know if that specs was correct, but it was a shot to see what would have been done in that situation. I think I can get a nice shot with the (1) teleconverter I have. Thanks for the reply

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