I got a hold of a very nice copy of this lens, and understanding it is an "easy" adaptation process, I figured I would try.
However I have read a few threads on it posted here in the last couple of months, and I canīt get my head around what is needed to be done.
There is talk of sanding off about 2 millimeters from the mount, there is talk about adding a shim (from what...?), I donīt quite seem to understand if I need to add or take away to get it to infinity focus on my 5D.
What about the long pin at the rear, that should surely hit my mirror? Should I clip it off? Remove it at the base somehow?
And this A/M selector. What to do about it? I wish to use stop down metering.
If anybody could enlighten me in a simple, clear way of the 55 FL-EOS process, that would be greatly, greatly appreciated
ovredal73 wrote:
I got a hold of a very nice copy of this lens, and understanding it is an "easy" adaptation process, I figured I would try.
However I have read a few threads on it posted here in the last couple of months, and I canīt get my head around what is needed to be done.
There is talk of sanding off about 2 millimeters from the mount, there is talk about adding a shim (from what...?), I donīt quite seem to understand if I need to add or take away to get it to infinity focus on my 5D.
What about the long pin at the rear, that should surely hit my mirror? Should I clip it off? Remove it at the base somehow?
And this A/M selector. What to do about it? I wish to use stop down metering.
If anybody could enlighten me in a simple, clear way of the 55 FL-EOS process, that would be greatly, greatly appreciated
Andre', sanding 2mm of metal off the lenses mounting boss can cause umpteen problems with fine sanding dust getting inside the lens, it wont guarentee the mounting boss stays perfectly flat and level and its likely to take such an eternity you might be left with bloody stumps where your fingers used to be!
You really need to machine the 2mm of metal off with a lathe...It only takes a few seconds, you get a perfectly flat and level mounting boss and almost no fine dust is produced at all, only larger swarf, so theres nothing small enough to get into the lens...But the lens should be wrapped and taped up in thick protective paper before turning anyway to prevent the extrerior getting scratched and prevent any fine dust that might be produced from getting in.
Jim Buchanan recently had a go at converting one following my lead:
But dont go entirely by his pictures because there is no need at all to dismantle the lens before performing the turning operation as once the lens is suitably wrapped in protective paper you can insert the lens, front end first, into the lathe chuck and clamp down with "just the right" pressure onto the aperture dial....Each of the three chuck jaws sits into one of the depressed knurled parts on the ring, preventing any possibilty of it slipping in the chuck.
Alf Beharie wrote:
But dont go entirely by his pictures because there is no need at all to dismantle the lens before performing the turning operation as once the lens is suitably wrapped in protective paper you can insert the lens, front end first, into the lathe chuck and clamp down with "just the right" pressure onto the aperture dial....Each of the three chuck jaws sits into one of the depressed knurled parts on the ring, preventing any possibilty of it slipping in the chuck.
OK, but how do you fine tune infinity focus, if you don't disassemble to get at the infinity stop mechanism?
JimBuchanan wrote:
OK, but how do you fine tune infinity focus, if you don't disassemble to get at the infinity stop mechanism?
There is no need to fiddle with the infinity stop mechanism at all...I'm sure you are aware that the registration distance of the Canon FL mount is 42mm and that the registration distance of both the Canon EF mount and Sigma SA mount is 44mm, so to allow the lens to reach infinity focus on a Canon EOS or Sigma DSLR you simply remove exactly 2mm from the lenses mounting boss, fit an EF or SA mounting plate on and voila...Job done.
BTW, the reason for the brass shim is because if you fit an SA or EF mounting plate straight onto the lens after the 2mm has been removed then you will find there is a tiny gap between the A-M ring and the bottom of the EF or SA mounting plate. This means the ring will have a tiny bit of up and down play which makes it feel sloppy with no torque resistance on the ring it easily keeps getting knocked to the A position where the lens wont stop down.
The shim is just a few thou thicker than this gap so when the plate is screwed down tight it clamps the A-M ring in the M position so the lens can be stopped down as required.
The shim came from an old Sigma SA mount lens and I could'nt believe it when I found it was exactly the right size for the job!
