Topic: Canon Fl 19mm f3.5R conversion to Canon EF
The lens:
from this webpage:
http://www.mir.com.my/rb/photography/co … /index.htm
Unfortunately, I didn't think to document the tear down of this lens, but it's pretty simple. Like many FL lenses, there's a nut on the very rear element, which, when removed, allows all the optics to slide out the front in a handy capsule.
In the first picture, you can see the "rear cup" which forms pretty much the main outer body. the focus helix assembly threads into it. first step is to remove the "step" shown below to allow the helix to thread further back into the outer body, thus allowing the optics to move further to the rear:
In order to do this (and you could with a dremel tool) I threaded the focus helix (brass) into the body for support, and used a parting tool on the lathe to cut this step off. In this way I had more support for the thin aluminum, as well as protecting the threads. There's an unthreaded area on the brass helix, so it's undamaged.
The second thing preventing the helix from screwing further into the outer body, is a snap ring groove behind the threads (snap ring no longer used) I used a boring bar to cut back this groove. Once again, you could do this CAREFULLY with your dremel
In the next shots below, we can see how the helix goes deeper into the outer body, the bottom of the inner cup now touches the bottom of the outer body on the backside:
The next thing we do, in the shot below, to move the optics to the rear, is simply mount the optics in the helix and swap the little brass spacer (factory) from the INSIDE of the cup bottom to the OUTSIDE, immediately under the retainer nut.
Below, we can begin to see "it all." This is the order of assembly. I've left off the outer focus control ring, and for now, do not know the calibration. I simply screwed the helix all the way to the bottom, and attached the outer focus ring to the closest "hole match" with the numerals past infinity. I may later re-drill if necessary to get the calibrations accurate.
In the shot below, the lens is temporarily together, waiting for the adapter in the mail. Here (on the right) is the assembled lens, and on the left, the damaged (second lens) outer body. The point is, the brass lug you see is the retainer which keeps the lens from turning as you focus. This PREVIOUSLY mounted on the INSIDE of the bottom of the outer body, and as you can see here, I've ground a clearance slot in the outer body, allowing the lug to mount on the OUTSIDE of the body. When the adapter (mount) arrives, I'll have to grind a clearance slot in the rear mount for that brass piece to clear.
Below, another shot of the nearly complete assembly. You can barely see the brass lug which retains the optics from rotating during focus, now mounted on the outside rear. The lens is lying on the old M/A ring, which may be later re-mounted. You can see how far in this first "try" the infinity mark is past the marker. Of course I'll have no idea how this relates until I get it mounted to the M39 -to- EF adapter
A couple of other notes: The outer body of this lens is rather small, so there's not really enough "meat" on an M42 adapter to leave room for screws, so I've ordered an M39 adapter. The original rear "M/A" control ring will no longer function. I'll probably, once tested and satisfied, simply epoxy that ring on the rear for "originality." What remains to be seen, of course, is whether this thing will be worth the trouble. I ALSO at this point have no idea whether this will clear the mirror on some cameras. I do not intend to install the original stop lug, so the villiage idiot will be able to simply unscrew the lens if not paying attention. However, I've determined that you'll be able to focus AT LEAST one full turn from "normal" and still be able to screw things back together.
Waiting for the adapter........
Last edited by 440roadrunner (2010-12-01 16:02:15)