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Posts: 5
Joined: Thu Mar 29, 2012 12:10 pm

Taped Pins On 1.4 Extender

Thu Aug 08, 2013 5:03 pm

Good day,

I am looking forward to purchase a 1.4x Extender and I found some interesting articles, which says that they can manipulate the data transferred from extender to body by putting tape on 3 first pins. The 3 pins being taped was intended to block electrical contact between the extender and the body itself. I have 70-200/4 IS and the f2.8 IS but I have no idea if its work or not, and I have a bunch of questions:

1. Does 1.4x Kenko Pro DGX and Canon III works with this trick?
2. Is this only fool the camera body but the maximum aperture remain decreased or fool the body with the maximum aperture actually not decreasing?
3. Is it works with 70-200/2.8L IS and 4L IS?
4. And finally, what are the penalties on using this trick? (eg. IS not work, noticable IQ decreasing, etc.)

AFAIK, this trick works on Canon 1.4x II + 70-200/4L IS combos, but I'm not sure this works on the Canon's Mark III, and I haven't seen any articles reviewing with Mark III yet.

Please share your thoughts and experience on using this trick. Any recommendations, inputs, advices, answers and contributions are greatly appreciated. Thanks.  

Posts: 4586
Joined: Fri Aug 27, 2010 12:26 am

RE: Taped Pins On 1.4 Extender

Thu Aug 08, 2013 10:53 pm

Canon extenders send a single to the camera which says what the effective aperture is. If the effective aperture is beyond the camera's autofocus limits, the AF will be switched off, and the camera will not attempt to focus.

For example, a 7D requires a aperture of at 5.6 or wider to focus. If you have an f4 lens and add a 2x convertor, the effective aperture is f8, so the camera won't focus.

You can force the camera to try and AF by blocking the aperture information by taping over the relevant pins (forget exactly which pins to tape).

But a few things to understand:

1 - in your example, using a 1.4 convertor, AF WILL work on any Canon camera - your worst case results in an aperture of 5.6 which is just fine. Taping the pins is not relevant for you. If you used a 2x convertor, that may be different. The pin tape trick only has a use with a 2x convertor.

2 - taping the pins has nothing to do with the optical qualities of the lens/convertor. The pins simply convey aperture information. Nothing more.

3- Canon does not block the AF function to annoy you. It is because the Canon AF cannot operate accurately, reliably at apertures smaller than it was designed to use. If you trick the camera in exceeding its design parameters, you cannot expect to get reliable results.



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