Question about Canon 100-400 IS lens

Hello,

I have read in a lens review forum that some kind of a "taping trick"
enables AF when using the 1.4 TC with this lens. Can anybody tell me what
this "trick" is?

Thanks,

--
Judit Fabian
University of Vermont
(802)656-9722

If you go to the website www.dpreview.com, go to the forums for lenses
and do a search for this there will be some posts with pictures. You
place tape ove the last 3 pins on the lens and it allows autofocus.

Judit Fabian wrote:
Hello,

I have read in a lens review forum that some kind of a "taping trick"
enables AF when using the 1.4 TC with this lens. Can anybody tell me what
this "trick" is?

Thanks,

Judit Fabian wrote:
I have read in a lens review forum that some kind of a "taping trick"
enables AF when using the 1.4 TC with this lens. Can anybody tell me what
this "trick" is?

Buying a EOS 3, 1v, 1D or 1Ds. ;-)

The other solutions is insulating the three additional contacts
the TC has, but do not expect anything than poor AF performance.


--
Helmut Faugel

Judit Fabian wrote:

I have read in a lens review forum that some kind of a "taping trick"
enables AF when using the 1.4 TC with this lens.

From: Helmut Faugel

Buying a EOS 3, 1v, 1D or 1Ds. ;-)

The other solutions is insulating the three additional contacts
the TC has, but do not expect anything than poor AF performance.

I agree with Helmut, the camera will TRY to AF and if there's enough contrast
it will do it, but it's not reliable. The bodies he mentions allow AF at f/8
min aperture, which is really nice.

Bill

Bill Hilton wrote:

Judit Fabian wrote:

I have read in a lens review forum that some kind of a "taping trick"
enables AF when using the 1.4 TC with this lens.

From: Helmut Faugel

Buying a EOS 3, 1v, 1D or 1Ds. ;-)

The other solutions is insulating the three additional contacts
the TC has, but do not expect anything than poor AF performance.

I agree with Helmut, the camera will TRY to AF and if there's enough contrast
it will do it, but it's not reliable. The bodies he mentions allow AF at f/8
min aperture, which is really nice.

In my opinion the 100-400 IS L is not sharp enough to warrant
any TCs. Just enlarge your straight image, it'll be just as good.

I just got the 300 f/4 L prime and it is much sharper.
(I do love the zoom of the 100-400, but I'll probably not
use it much anymore).

Roger

Jim Davis wrote:

On Fri, 07 Nov 2003 21:48:12 -0700, "Roger N. Clark"
wrote/replied to:

In my opinion the 100-400 IS L is not sharp enough to warrant
any TCs. Just enlarge your straight image, it'll be just as good.

at times I think the same but sometimes when I have enough light and a
tree to steady against my results with a 2X are superb. Way better
than just enlarging the lens without.

I just got the 300 f/4 L prime and it is much sharper.
(I do love the zoom of the 100-400, but I'll probably not
use it much anymore).

Did you get the IS model? I heard that's not such a sharp lens, heh
heh. Hey, I'm not being picky here, but some people are. How sharp is
sharp enough anyway? I can make excellent 12 by 18 photos with the
100-400, and that's good enough for me. yes, with 2X I can also make
12 by 18s.

Yes, the IS model. I do my testing on a tripod and use both real
scenes and test targets. With a 10D, which has spatial
resolution similar to ISO 50 Velvia, the 300 f/4 is sharp
down to the pixel at f/4. The 100-400 is blurred by several
pixels, especially at 400. I can make really nice 8x10s
with the 100-400, but it is soft above that. As a large format
photographer, I'm pretty picky about sharpness.
See images, articles on sharpness and test results at:
http://www.clarkvision.com

Roger