I finally got the parts and tools together, and got this rig together.
I have a Canon FL Bellows with a slide duplicator on the end, and a Sony NEX mirrorless camera. Fortunately, the NEX isn’t too picky about accepting other lenses, so long as you have an adapter that ends in an E mount.
I followed the advice in this post on the Fred Miranda forums (which I mentioned earlier), and I figured I would elaborate on how to attach the L39 to NEX mount on to the Bellows FL, because the OP didn’t really go into much detail.
First, get an L39 (Leica Screw Mount) to NEX mount adapter. There are tons of them out there. I got a Fotodiox adapter for about $20 on Amazon. You want one with a shiny metal liner (which the L39 lens would screw into) that’s held in place with 3 grub screws. (Grub screws are headless screws that are buried in little holes on the sides of the barrel.)
To back out the grub screws, you’re going to need the tiniest screwdriver you can get. In my case, I needed a 0.7mm hex head. It’s just the head– it can be screwed into a handle, or you can just use the bit. I found mine at Harbor Freight as part of one of those microtool interchangeable head hand tools.
It also helps if you have a really bright light, and a magnifying glass. You’re going to be dealing with a lot of tiny screws.
Ok, Got Your Stuff? Let’s Install It!
First, remove the FL mount ring. It’s the shiny metal ring on the back of the FL Bellows. Start by removing the two screws holding the handle on, remove the handle, then remove the retaining screw on the ring. Back the ring out by unscrewing it clockwise. (Righty-loosey for once.) The ring should come off pretty easily. If it gets really tight, you’re turning it the wrong way.
When the ring is removed, there should be one little flat-head screw left at the top of the remaining mount. It will poke out into the area you’ll be mounting the L39-NEX adapter, making it impossible to get the adapter to hold on, so back it out. Take all of these parts and store them in a little baggy. Or recycle them. It’s up to you. (I’m in the baggy camp.)
Back out (but don’t remove!) the grub screws in the L39-NEX mount until the threaded shiny liner pops out. You may need to use a tool with a handle to get enough torque to break the seals.
Now you need to attach the NEX mount to the end of the bellows. It’s more of a matter of positioning the mount and making sure the grub screws are tight. There are two tricky parts here.
First, the bottom right screw is hard to get at when the mount is in the correct position. I used just the head of the driver tool. The bellows hardware gets in the way otherwise.
Second, the red dot on the mount needs to be in the right position. I put it right around 9 o’clock on the ring. To get it close enough, I mounted the NEX and carefully backed out one of the grub screws a hair, then gently moved the mount until everything was parallel and square.
I suppose you could add something like Loctite or JB Weld to make sure it never comes off, but in 5 years some other mount may be the favorite of the day, so I would advise against doing that.
What’s going on here is that the grub screws from the mount are grabbing the end of the old FL mount, which is a smooth tube. It’s a friction fit, so don’t torque it too hard, and be careful when using it for shooting. (Support everything!) I have no idea how prone this setup is to falling apart– only 3 tiny screws are holding the whole thing together.
I dropped in a 35mm f3.5 lens and checked out a test slide, and it fits in the frame just fine now. There’s just enough distance between the bellows and the sensor now that I can get the whole slide duplicator in the frame. I’ll try the 50mm f3.5 macro later and see how it works.