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Author Topic: Canon Extender EF 1.4x II Compatibility  (Read 8086 times)

paulbk

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Canon Extender EF 1.4x II Compatibility
« on: May 26, 2006, 07:57:58 am »

I am considering the new Canon 1.4 II Extender for my 70-200 f/2.8L.
Why is Max. Magnification different for the USM (.022) and the IS USM (0.24)?

Canon Extender EF 1.4x II Compatibility Chart
EF 70-200mm f/2.8L...........USM......... IS USM
new Focal Length(mm).......98-280..... 98-280
new f-stop(f).......................4-45........ 4-45
new Max. Magnification(x)...022......... 0.24

B&H Info, click Features, then click Compatibility Chart Note:
Compatibility Chart
« Last Edit: May 26, 2006, 07:59:07 am by paulbk »
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paul b.k.
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Ronny Nilsen

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Canon Extender EF 1.4x II Compatibility
« Reply #1 on: May 26, 2006, 09:55:21 am »

EF 70-200mm f/2.8L IS USM  Closest Focusing Distance 1.3m / 4.3 ft
EF 70-200mm f/2.8L USM  Closest Focusing Distance 1.5m / 4.9 ft.

Closer focus -> more magification.  
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Ronny A. Nilsen
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paulbk

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Canon Extender EF 1.4x II Compatibility
« Reply #2 on: May 26, 2006, 02:50:23 pm »

re: Closest Focusing Distance 1.5m / 4.9 ft.

Ron,
My 70-200 f/2.8L USM manual says:
Min. Focus = 0.38 m (1.25 feet) ... assume with min. focus switch in 0.3 m position

Are your numbers with the 1.4 extender on?
If so, where did you get them?
Are they printed in the 1.4 extender manual?

I didn't know that "IS" changes min. focus. I have no IS gear, but lust after it.

Also... I have visited your web site, outstanding! And I very much agree with your philosophy.
« Last Edit: May 26, 2006, 02:55:24 pm by paulbk »
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paul b.k.
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Gary Ferguson

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Canon Extender EF 1.4x II Compatibility
« Reply #3 on: May 26, 2006, 05:03:59 pm »

The Canon lens book, "EF Lenswork III" gives the closest focus distances as 1.5m for the 70-200 2.8L, and 1.4m for the IS version. So it's the same answer but with different numbers. The extender will have no effect on closest focusing distance, so it will increase magnification.

"EF Lenswork III" is also a source of MTF curves for most Canon lenses with both the 1.4x and 2.0x extenders. Looking closely at the charts it seems the x1.4 is a slightly better match for the non-IS 70-200 2.8L than for the IS 70-200 2.8L. There's not a huge amount in it but it looks like the non IS version is slightly superior at both the wide and tele ends of the zoom range. I've used the IS version with the 1.4x and if you'll be getting better results than that you should be delighted, it's an impressive combination.
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Ronny Nilsen

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Canon Extender EF 1.4x II Compatibility
« Reply #4 on: May 27, 2006, 03:37:02 am »

Quote
re: Closest Focusing Distance 1.5m / 4.9 ft.

Ron,
My 70-200 f/2.8L USM manual says:
Min. Focus = 0.38 m (1.25 feet) ... assume with min. focus switch in 0.3 m position

Are your numbers with the 1.4 extender on?
If so, where did you get them?
Are they printed in the 1.4 extender manual?

I didn't know that "IS" changes min. focus. I have no IS gear, but lust after it.

Also... I have visited your web site, outstanding! And I very much agree with your philosophy.
[{POST_SNAPBACK}][/a]

Thank you for the kind words.

I got the numbers from the [a href=\"http://www.usa.canon.com/consumer/controller?act=ProductCatIndexAct&fcategoryid=111]Canon USA[/url] site. Pick a lens and go to Product information ->  Specifications.

As Gary said, the extender do not change the close focus distanse. I have the IS version and the 1.4 and it's really a good match and i belive you will be happy with the 1.4 extender on your lens as well.
« Last Edit: May 27, 2006, 04:19:55 am by ronnynil »
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Doug Kerr

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Canon Extender EF 1.4x II Compatibility
« Reply #5 on: May 27, 2006, 08:41:26 am »

Hi, Gary,

Quote
The extender will have no effect on closest focusing distance, so it will increase magnification.[a href=\"index.php?act=findpost&pid=66663\"][{POST_SNAPBACK}][/a]
Indeed, the extender doesn't effect the closest focsuing distance as measured from the first principal point of the lens, which is the distance that affects the maximum magnfication of the main lens itself.

That magnfication is then "multiplied" by the multiplication of the extender. (That is essentially how the extender multiplies the focal length!)

Adding the extender does change the closest focsuing distance as measured from the focal plane (which is how focusing distances are usually stated), just because it moves the main lens physically outward by the "length" of the extender (and thus moves out the first principal point, which remains in the same place in the main lens).

Please excuse my introduction of the term "main lens". The tradiitional technical term for that  is "prime lens". but of course that term has in modern times been hijacked to mean "a lens of fixed nominal focal length"!

It shouldn't be surprising that the minimum focusing distance of the two lenses cited would be different, since they have different optical desgns. (It is not as if the IS feature were something "bolted on" the outside of the lens.)
« Last Edit: May 27, 2006, 08:43:26 am by Doug Kerr »
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Best regards,
 Doug  Visit The Pumpkin
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