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Author Topic: Canon 70-200 F/4.0 IS USM  (Read 3886 times)
eagle6
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« on: November 26, 2006, 12:47:35 PM »
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I am new to the forum and WOW, such a wealth of information so far......


My question is, I have just ordered a new Canon 70-200 F/4.0 IS USM lens and want to find a 1.4 and/or 2.0 teleconverter. I have read that the Canon Tcons
will not work with this lens. I am considring the Kenko Teleplus Pro but cannot find
anything that says for sure it will work with this lens.

Does anyone have any information to to assist me?

Are there any other Tcons that someone might recommend for this lens?

Thanks so much............
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Jack Flesher
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« Reply #1 on: November 26, 2006, 01:15:24 PM »
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I am new to the forum and WOW, such a wealth of information so far......
My question is, I have just ordered a new Canon 70-200 F/4.0 IS USM lens and want to find a 1.4 and/or 2.0 teleconverter. I have read that the Canon Tcons
will not work with this lens. I am considring the Kenko Teleplus Pro but cannot find
anything that says for sure it will work with this lens.

Does anyone have any information to to assist me?

Are there any other Tcons that someone might recommend for this lens?

Thanks so much............
[a href=\"index.php?act=findpost&pid=87180\"][{POST_SNAPBACK}][/a]

Buy a Tamron converter or do a Google on taping canon pins...  You will read about how to tape the last three pins on the camera side of the Canon teleconverters (not the three on the raised block, but the three at the opposite end).  You do *NOT* need to do this with 1-series bodies, but will with 5D/30D/Rebel.

Cheers,
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cdees
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« Reply #2 on: November 26, 2006, 02:02:28 PM »
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The Canon 1.4x will work flawlessly on every body. There will be only very little decrease in IQ and AF.
The Canon 2.0x will only work on a series-1 body. There will be a lot decrease in IQ and AF. It's not recommended.
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David White
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« Reply #3 on: November 26, 2006, 02:13:50 PM »
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The Canon 1.4x will work flawlessly on every body. There will be only very little decrease in IQ and AF.
The Canon 2.0x will only work on a series-1 body. There will be a lot decrease in IQ and AF. It's not recommended.
[a href=\"index.php?act=findpost&pid=87191\"][{POST_SNAPBACK}][/a]

This is wrong.  The 2x will work on all canon bodies.
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David White
Jack Flesher
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« Reply #4 on: November 26, 2006, 03:17:56 PM »
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This is wrong.  The 2x will work on all canon bodies.
[a href=\"index.php?act=findpost&pid=87192\"][{POST_SNAPBACK}][/a]

Oh boy...

Only the 1 series bodies will AF with effective apertures of f8.  The lower bodies need f5.6.  Somewhere in there, and I do not know all the specific ins and outs, some of the lesser bodies will only allow combinations of center-point and/or single AF at f5.6.  AFAIK, all current bodies will offer full AF options at f4 or wider.

So, if your TC/Lens combo is f8 -- like the 70-200 f4 with the Canon 2x -- it will not AF unless you tape the pins or use a 3rd party converter without the extra data pins to begin with.
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eagle6
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« Reply #5 on: November 26, 2006, 03:33:26 PM »
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Tks for the hints, sounds like the Tamron Tcon may be the way to go.

If I have read various info correct, I should only loose 1 f-stop with the 1.4 and 2 with the 2.0............

I looked at the Tamron Tcon on the internet and they have a SP AF pro series,
I would guess that would be the best way to go as I don't want to degrade the quality of the L glass that I have payed so dearly for.
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jani
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« Reply #6 on: November 26, 2006, 05:02:32 PM »
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Tks for the hints, sounds like the Tamron Tcon may be the way to go.
Problems with autofocus will persist even with third party teleconverters, in the form of focus "hunting", but yes, the Tamron models will "lie" to the camera about the effective aperture (strictly speaking, the lenses just pass on the EF signals).

A few considerations:

There apparently are two different Tamron models out there; one 7-element TC and one 4-element TC. According to comments I've seen, the 4-element TCs aren't good, and both Canons are better than the better Tamrons in terms of image corner sharpness.

Tamron TCs fit a wider range of lenses.

All TCs degrade the quality of the L glass that you've paid so dearly for. It's only a question of how much image quality loss you're willing to accept.

Caveat lector: I have not tested the Tamron TCs myself.
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Jan
eagle6
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« Reply #7 on: November 26, 2006, 09:30:26 PM »
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Jani,  
You've got me thinking now...................

Do you know anything about the Kenko Telepro series?

I sure would rather stick with Canon, but their converters don't fit
from what I am being told. I guess I could consider "taping" the
contacts like was mentioned in a previous thread, but that just doesn't
feel like the right thing to do, I don't know...................

Why is it that Canon would make converters that don't even work
with their own lenses?HuhHuhHuhHuhHuh??

Open for any sugestions at this point.
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phila
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« Reply #8 on: November 27, 2006, 01:48:01 AM »
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Why is it that Canon would make converters that don't even work
with their own lenses?HuhHuhHuhHuhHuh??

*******

It is simply optical physics.

You need a certain level of light reaching the AF sensors for them to work. With the 1.4X there is still enough. With the 2X there isn't.

I use the 1.4X with my 70-200f4 (non IS but the same as far as TCs are concerned) and it works beautifully! By works I mean producing an extremely good image - not quite as good as the lens by itself, but very usable. AF speed is automaticaly slowed to suit the "new" optical system.

My experience is to ALWAYS match Canon TCs with Canon lenses (Nikons with Nikons, etc).
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jani
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« Reply #9 on: November 27, 2006, 03:46:42 AM »
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Jani,  
You've got me thinking now...................

Do you know anything about the Kenko Telepro series?
No, sorry.

Quote
I sure would rather stick with Canon, but their converters don't fit
from what I am being told.
Instead of relying on others, go straight to the source:

http://www.usa.canon.com/app/pdf/lens/EFLensChart.pdf

The EF 70-200 f/4L IS USM isn't listed in this chart yet, and I must admit that I haven't seen any mention of compatibility or incompatibility with the EF extenders elsewhere.
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Jan
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« Reply #10 on: November 27, 2006, 03:50:10 PM »
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It is simply optical physics.

You need a certain level of light reaching the AF sensors for them to work. With the 1.4X there is still enough. With the 2X there isn't.

[a href=\"index.php?act=findpost&pid=87313\"][{POST_SNAPBACK}][/a]

Now this just can't be the whole explanation.  If I can focus at f/5.6 at night when I have to expose for seconds, then surely f/8 will allow enough light during the day to focus, if the level of light is what matters.  In bright sunlight, will a low-end SLR using lens plus TC to make f/8 the widest aperture focus?  And if it's not just the level of light (as in, raw number of photons) that determines AF ability, what is it?  Angle of the light?  A combination?

-Lars
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eagle6
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« Reply #11 on: November 27, 2006, 05:01:34 PM »
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An update on informaton I received from Canon support is telling me that
the Canon EF 1.4X II tele extender IS compatible with the 70-200 F/4.0 IS USM.

They said that AF will work but if I go the the 2.0 extender, it will not.

I just canceled my Tamron order and have ordered the Canon.

Will update again on results.

Tks for all your feedback and tips
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jani
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« Reply #12 on: November 27, 2006, 05:17:15 PM »
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Now this just can't be the whole explanation.  If I can focus at f/5.6 at night when I have to expose for seconds, then surely f/8 will allow enough light during the day to focus, if the level of light is what matters.  In bright sunlight, will a low-end SLR using lens plus TC to make f/8 the widest aperture focus?  And if it's not just the level of light (as in, raw number of photons) that determines AF ability, what is it?  Angle of the light?  A combination?
Autofocus is contrast based.
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Jan
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