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Old Mar 15, 2005, 7:13 AM   #1
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I am looking to buy a Sigma 1.4x converter. But the 'blurb' says:


Sigma Apo Tele converter 1.4x EX and 2x EX should be used only with lenses listed above. If you mount a Sigma Apo Tele Converter 1.4x EX or Apo Tele Converter 2x EX to a lens that is not listed above, it may damage the lens element of the Tele Converter as well as the master lens.

Is this true ? If so, why ? If not, why do they say it ?

If it is true, is that the same for the Canon 1.4x TC ?

Thanks for any info

Alan
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Old Mar 15, 2005, 8:37 AM   #2
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alan sh wrote:
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Is this true ? If so, why ? If not, why do they say it ?
It's true

There's more correcting 'glass elements' in theses matched converters than a 'generic' TC -> ie it's thicker than the outer metal barrel, and will protrude into the main lens.

If you mount theses TC's on lenses other than listed its 'glass elements' will butt againts the back of the main lens when you focus or zoom!!!



Quote:
If it is true, is that the same for the Canon 1.4x TC ?
The Canon's TC are even thicker internally than the Sigma, and won't mount on a Sigma 70-200 f/2.8 (but a Sigma TC will work on a Canon)



BTW both 2x are much thicker internally than their 1.4x counter part...
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Old Mar 15, 2005, 11:05 AM   #3
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The only thing I'll add is that the Sigma 1.4x will work with some Canon lenses. The problem I've run into is this: when I bought my sigma 1.4 from b&h the list of lenses included both sigma and canon lenses. Silly me I didn't print it out. I now see that both B&H and Sigma only post the sigma lenses the teleconverter works with. Anyone have that old list that shows the canon lenses (also should show whether AF still works).
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Old Mar 15, 2005, 11:19 AM   #4
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The Sigma TC will work with the same Canon lenses as the Canon TC, so if you can find the Canonlist you should havethe answeryou need.

Basically the TC's will only mate and work with the Canon L series lenses.

Peter.
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Old Mar 15, 2005, 2:36 PM   #5
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PeterP wrote:
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The Sigma TC will work with the same Canon lenses as the Canon TC, so if you can find the Canon list you should have the answer you need.

Basically the TC's will only mate and work with the Canon L series lenses.

Peter.
Since the Sigma 1.4 is over $100 cheaper than the Canon 1.4, and works on the same lenses, why do people buy the Canon:-)? Is it that much better quality?
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Old Mar 15, 2005, 2:52 PM   #6
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KM_krazy wrote:
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why do people buy the Canon:-)? Is it that much better quality?
For one it matches the white lens - IMO black/white combination look kind of odd either way...

Stick with 1 color :blah:
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Old Mar 15, 2005, 3:56 PM   #7
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NHL wrote:
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KM_krazy wrote:
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why do people buy the Canon:-)? Is it that much better quality?
For one it matches the white lens - IMO black/white combination look kind of odd either way...

Stick with 1 color :blah:
just get some white-out. . .:blah::lol:
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Old Mar 15, 2005, 4:29 PM   #8
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PeterP

A clarification - The TC's will only work with Canon L series tele/zoom - It won't work on a 24-70 f/2.8L for example...


Quote:
(also should show whether AF still works)
AF will work if the resulting aperture is larger than f/5.6 on the 20D and below - Aperture smaller than f/5.6 is un-reliable although some cameras may be able to do it. It's not because there isn't enought light but for not having enough defocus info from the side angle for the camera to work with.

Remember the split-screen viewfinder? One can put an ND filter on an f/2.8 lens so that the light coming through is darker than an equivalent f/8 lens and it would focus just fine - but an f/8 can't AF focus even if one gives it all the light in the world
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Old Mar 17, 2005, 2:12 AM   #9
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Does anyone know anything about the quality between the Sigma vs. the Canon?
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Old Mar 17, 2005, 6:06 AM   #10
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I don't know about the other brands, but here's a Sigma 2x matched to its 120-300 f/2.8 shot wide open: http://www.stevesforums.com/forums/v...48&forum_id=65

It's good enough for me... :idea:
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