Canon EF 50mm f/1.2L USM converted to SA mount!!!!

Started Aug 13, 2007 | Discussions thread
Gunter B Contributing Member • Posts: 951
Re: Manual focus?

Thanks Jerry.

I have successfully converted a Canon 50/1.4, which I am very happy with.

Now that I know it works, I will probably get an 135/2. It is my dream lens, being tacksharp at f2.

Arky wrote:

Hi Günter,
I have converted the 135 f/2, its a fairly easy conversion since it's
rear optics are recessed into the lens instead of protruding into the
mount like most lenses. 3 of the 4 screwholes will line up with the
SA mount but the top screwhole will need to be drilled and
counter-sunk just like Daiver has done with his 50mm. It will focus
to infinity with the standard SA flange but the range scale on the
lens will show the lens to be focused a little past infinity. If you
want the range scale to be accurate you will need to shave the mount
down a little thinner, especially around the outer edge.
The 135 is a "TC aware" lens so it has a 10 circuit electrical
contact block, you will probably be replacing it with a standard
(non-TC aware) 7 circuit sigma contact block. The extra 3 circuts in
the 10 contact block are there solely to detect the presence of a TC.
If you just leave these extra 3 wires unconnected (tape the ends to
avoid shorting) the lens will not "see" a TC and the AF will operate
at full speed, I have heard the SD14 AF works fine with this lens at
full speed. The SD9 and SD10 however, cannot control this lens when
it's AF is operating at full speed, for those cameras you will need
to slow down the AF motor by fooling the lens into thinking it is
attached to a 1.4x TC. To make the lens think it is attached to a
1.4x TC simply solder the extra 3 TC detection circuit wires together
(again tape the end to avoid shorting) and tuck them away inside the
Hope this helps, don't hesitate to ask if you have any more questions.

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