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Rokinon Sigma SA mount conversion
Old 03-16-2018   #1
shawn
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Rokinon Sigma SA mount conversion

I had a PM about my SA mount converted Rokinon 14mm lens on the SDQH.

It is a fairly easy conversion to make. You need a Canon EF mount Rokinon 14mm lens.

Then one of these.

In that kit is a PK mount base plate that has a small threaded lip on it as you can sort of see on the base plate on the right.



I mount that base plate to the other end of the extension to give me a way to easily hold the plate. Then I use the side of a bench grinder to remove most of that lip from the plate. Final removal is with a diamond hone to get it flush with the plate as seen in the picture on the left above.

After it is flush and cleaned up mount it into the SDQ. Mark the top of the plate with it mounted in the camera. The line on the camera body is not the top of the plate. Use a square to find the top with the camera sitting on a table. If you get this off the lens hood will be slightly uneven, doesn't matter with the 14mm but looks a little odd.

After that you want to find and mark the top of the Canon mount plate in the Rokinon and then remove the plate by taking out the three screws.

Put the Canon mount and the Rokinon mount back to back (flat sides together) and mark your three drill holes. I tape them together and use the Canon plate as a drill guide for my drill press. After you drill the three of holes you need to drill countersinks on the new plate. MAKE SURE YOU DRILL THE COUNTERSINKS FROM THE LENS MOUNT SIDE.


(Ugly drill job)

After that is done I used a 0.1mm brass spacers (McMaster Carr) under the SA mount plate and attached it to the camera.



Infinity focus point was right on the money. If it is off slightly, or you want infinity to be at the focus stop it is very easy to adjust on the 14mm.
If you look at any online guide they have you fold the rubber focus grip toward the back of the lens to expose three set screws. Then they show a port to adjust focus. That port really isn't to adjust focus, it is setting the limiter position. To better calibrate focus (and the focus scale) Loosen those three screws and then set the lens to minimum focus distance. While zoomed in on a distant object slowly turn the lens toward infinity. At some point you will feel a click as you make contact with the limiter. The lens will keep turning with those set screws loose. As you approach infinity (visually, ignore the scale) be sure to not turn the dial back toward closer focus, that will mess up the limiter position. If you need to go back make sure you turn the lens all the way back to minimum distance to reset the limiter position and then try again. Once you have a distance object well in focus don't touch the dial and tighten in those three screws. You should find that the lens will no longer move past infinity.

To calibrate the focus dial is easy. Push the folded over rubber focus ring toward the front of the lens with it still folded over. You should see a seam above the focus distance scale. It is taped to the dial above it. Cut through the tape and the focus distance scale ring will turn freely. Set the lens to actual infinity (against the stop) and then turn the focus distance scale so it is reading infinity. Use a couple of pieces of tape to hold the dial together. Push the folded over rubber focus ring toward the rear of the lens and then unfold it and you are all set.

The adapted plate will also work on a Rokinon 8mm fisheye. If you have a SDQH make sure you get the version that allows you to remove the lens hood or you will get a ton of vignetting on the SDQH. You will still have black corners with the FE though.



Shawn
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