Lens Hacking: Canon FD to EOS!

Hunter Hampton

Hunter Hampton

Carbonite Member
I love using canon FD lenses, especially my 50mm on the gh1/2. But I also shoot on a 5d and 7d/t2i often and It makes me really sad that I cant use my favorite fd lenses on EOS (with out using a crappy glass extender).

So ive been looking at some lenses that had already been professionally converted to EOS and they cost quite a bit to convert compared to their price ($275 per lens for just the conversion) - that is a bummer because I think I only paid $75 for my 50mm f1.4.

After doing a lot of googling I found some people who have successfully converted the lenses, but It was really hard to see what they were doing- some people just made them "wide open" only lenses- used lens caps for the mount- not what I want.

Last night I decided to just pop all the lenses open and start the process- this could all completely be a failure- and if it does, ill need the sympathy from people like you because I would have lost some of my favorites.

Warning- this is going to be a sloppy but completely functional conversion- The right way to do it would be by machining parts, countersinking screws, ect... Im not machining anything because my "machine shop" only exists only as a drimmel. Ill be using JB weld to make permanent modifications. This could get ugly- dont try it until you see if I fail or not.


135mm f2.8
I started with the 135mm f2.8- I just made a new aperture linkage last night and it seems to be working great- this was a weird linkage to the ring because it travels up and down as the lens focuses, so I ended up breaking off a peice from the old lens mount and bending it to make a link that has a guide rail. Probably will take me a few days, but im going to tell you exactly what I am doing. Later today Im going to set the mount and find/make the right shims.

Aperture linkage works well by the way! I also declicked the lenses during the process of removing the old mounts.


Work in progress... more info soon.
 

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Quick overview of the process and why you have to hack up FD lenses to convert them to EOS:

Canon EOS has a 44mm Flange Distance- Canon FD has a 42mm Flange distance- that means if you just made an FD->EOS lens adapter- you would only be able to use the lens as a macro and you couldn't focus more than a few feet (there are glass extender FD->EOS versions but they lose light and lower the image quality too much unless you stop down significantly)

So you need to actually remove part of the FD lens to make it short enough to be used with an eos mount. Theoretically at least 2mm.

I did that by removing the old mount: 3 screws around the lens, pull the fd mount off- then the Auto aperture linkage junk can be pulled out and you have a bare lens- just a helicoild with a non functional aperture ring and no mount.

Good news is after you reconnect the aperture ring, you can add and shim to get a proper distance surface for adding an EOS mount.

I found the perfect size shim at ace hardware, just a steel washer- surprisingly- I think once the JB weld is used this will be exactly the distance needed to hit that 44mm flange focal distance I need. The JB is doing its thing and tonight I will mount the new EOS mount- and hopefully have a functional EOS 135mm f2.8 in the morning!
 

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Mount is setting... I hope I got the FFD right (the bad thing about using JB weld!)- Ill let it rest and try it on my camera in the morning. If I mess up this, at least its only my 135mm and not my 50mm.
 

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Thank you Dr. Frankenstein. I have some great older fd lenses and they are cheap since they dont mount nicely to the EF mount. If this works out it may be a real option for my old 50mm 1.8 and some of my other lenses. Any sort of instructions would be helpful.

Thanks!
 
Great News! My 135mm f2.8 FD is now a fully functioning 135mm f2.8 EOS mount lens. Infinity focus is good- feels solid. Now Im just waiting for some new eos mounts to finish the rest of the lenses!

Ill try to give a tutorial after I make a few more mistakes- one thing though is a lot of the lenses are different so there isnt one specific way to do it.
 

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Congrats! The only thing i was really concerned with is getting the distance from the back of the lens to the chip dead on. If thats off i thought you would lose infinity focus
 
Hey Hunter,

I've converted a couple of lovely Minolta f1.2 58mm lenses to EOS, as they were also a shorter flange distance, similar to FD. I bought a couple of EOS to M42 adapter and used them as the mounts, detached the Minolta mount and used JB weld, but also drilled & countersunk holes through the new adapter and into the original lens mount holes on the lens.

If, as is usually the case, you don't quite hit the perfect infinity at the end stop of your focus scale, it can be adjusted by loosening the helicoil, repositioning and re-tightening in perfect collimation. The helicoil connecting screws are usually the three screws under the rubber focusing grip. You can get it perfect by doing that, in case you don't hit the spot next time. I hope that helps. Nice job! Lucas
 
hunter richards said:
Thanks for the tips Lucas! How is that Minolta, got any pics?
Click to expand...

Sold them, I'm afraid.

You may have some trouble if you plan on converting lenses wider than 35mm focal length from FD to EOS - that's the case with the Minoltas, and even some of the Contax lenses which have a deeper flange distance. The rear element protrudes further on wide-angle lenses.
 
Im just waiting on some more mounts so I can convert my other ones, I think my friend will let me convert his 50mm fd too so maybe I can do a complete tutorial on that (given I dont completely mess up my 50mm).
 
Congratulations, sir. You are either brave, or foolish. Since it worked, I think we should stick with brave.

Nicely done, I'm impressed :)
 
Hunter, after buying an anamorphic lens from you and now this so i can mod all my old FD lenses. You could be my favorite person of the week...
 
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