FD to EF EOS Lens Mount Conversion
From what I understand, a lot of manual focus lens users and long time Canon users (that used the FD system) would be interested in possibly doing a similar conversion. For those of you wondering, here's how I did it.

First, we must understand why we are doing all of this. The reason is that the flange focal distance (the distance that the optical stuff in the lens must be away from the sensor or film plane to infinity focus correctly) for the FD system is 44mm, while it is 42mm for EOS. This means that the FD lens must be made 2mm closer to the lens (keep in mind that we must take the new mount that we must add into account, which will probably add another mm or so). To make the optics closer, we have to remove a bunch of stuff of the back of the lens. Now onto how it's actually done...

Note that this lens was a bayonet mount (black, non rotating) FD lens, not the breech lock mount (that's the one with the silver rotating mount).

I started by removing the three screws around the outside of the mount ring. The silver ring inside of the mount will now be loose, pull that out, as well as the aperture linkage stuff. Now you are down to the actual aperture stuff. The second picture in this set is what the lens will look like. If you want a fixed aperture lens you can skip right down to the part where I actual mount the lens, otherwise I recommend you keep reading.

I then attached the plastic outer ring to a metal ring in the middle and attached that to the golden colored piece that actual controlled the aperture. I understand that this next part may make no sense to someone just reading this, but if you have the actual lens at this stage, it will. To connect the metal ring to the aperture control you have to create a little loop with something (I used a paperclip) and loop it over the little area sticking up on the aperture control. Glue the piece to the metal ring. This is all so you can properly focus (the optics need to move forwards and backwards to focus) while still being able to adjust aperture.

Now we are at the mounting stage. It is crucial that you hold the lens up to the camera (with the mount attached to the camera) to see if it will infinity focus correctly before mounting. I took MORE than the 2mm off so I needed some spacers so it would correctly focus. I tested several washers and eventually found some that were the perfect thickness. I used a bolt cutter to cut them to sizes about the size of the green highlighted areas on the second picture in this stream. I glued those pieces onto the green highlighted areas. Finally it's time to actually mount the camera. I did one last test first to make sure everything was working well. I then took an m42 to EOS adapter (a few dollars on ebay) and glued that to the washer pieces that I had previously glued on. It has worked successfully for the past few days, please check out some of the pictures that I've taken with it (there's a set on my Flickr page).

I hope my tutorial helped!

-Evan
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