Using a Canon FD lens on GH1

K

kabacam

Member
Can someone explain just how a Canon FD lens works on a GH1? Once I attach an adapter and set "shoot without lens" will I have aperture control? Thanks, John
 
I would also point out that if you are used to controlling aperture on AF lenses then you are probably used to 1/3rd aperture stops.

On a manual lens you can adjust the aperture ring so it is between stops.

The FD to micro 4/3rds adapter that I used is this one
http://cgi.ebay.com/Canon-FD-FL-G1-...ccessories&hash=item3a5bec6335#ht_3196wt_1139
!BqmsbjQ!mk~$(KGrHqEOKkEEuZu4Z5BVBLwLTHOYGQ~~_12.JPG

.
 
Last edited:
Also it's quite easy to modify most FDs in order to remove the stop-clicks thus giving you a smooth turning aperture ring!
 
And when attaching the FD to the micro4/3 adapter, please make shure that the protuded pin seen inside the adaptor engages well with the stop-down lever of the FD lens. If not, the FD's aparture will be in a wide open position only.
 
emory said:
How is this done? I'm finding the half-stop click stops too coarse.
Click to expand...

Sorry, I missed this. Yes, besides the smooth ring on some adapters you can do this mod to many FD lenses directly - actually most manual lenses containing an aperture ring.

Each lens is a little different so it depends on the lens as to how you go about the modification. There seem to be two common types that I run across a lot.

  • One uses a brass leaf spring with a depressed "bubble" in it. This bubble rides along on a ridged plate. To mod this one you need a pair of flat needle-nose pliers with about a 3mm wide tip. By flat I mean no gripping teeth (ridges) on the inside of the pliers' jaws. Remove the mount, be careful of any attached helical springs (some are brazed into place), and reach in and crush that bubble with your pliers. If you scratched the surface of the leaf-spring just use your pen-router with a fine stone attached and take off any burs. It's best to use a cylindrical shaped stone:

    _1010697.jpg

    And use the buffing bit with some polishing compound after to make it nice and mirror smooth. If it's black metal instead of yellow brass you'll have to grind t off as it probably won't be crushable.

    This design seems to be popular on cheaper lenses.




  • The other type is a pressure spring and seated ball. I usually see this on higher grade lenses and is much easier to deal with. Here, this ball rolls over ridges or indentations for the stops. All we need do is remove the ball and we're golden. This is usually a very easy mod.


    Remove the mount - again be careful of brazed on springs (rare on good lenses tho occasionally encountered).

    _1010704.jpg



    Remove the aperture ring and locate the pressure spring & ball assembly. It's often two seated and keyed rings together (pay attention to how it comes apart in case it's not keyed):

    _1010700.jpg



    Remove the pressure spring:

    _1010701.jpg



    And poke the ball out from the other side with an ice-pick or something:

    _1010702.jpg



    Here's the assembly from the other side:

    _1010703.jpg

    Then just put it all back together (minus the ball) and you're cool. As you reassemble it make sure things turn to their proper positions and etc. It's also a good idea to take pictures at each stage of the disassembly in case your grandson or someone flies into the room and knocks everything over. :)



Also if you'll notice on the grooved (pitted) side of the sleeve race, there may be a stop screw as there is on this one (sometimes there is one for min and max apertures):

_1010704.jpg

These can often be relocated or removed to allow more ring travel. On this particular design (see bottom right black stop-screw) the next hole over gives f/32 as opposed to the original f/22 limit and placing it in the farthest hole over allows the blades to close completely (C). You can use a mod like this at (C), for some interesting video effects. It's a bit like a fade from black effect but also backs out from infinite focus depth to whatever DOF range you stop turning the ring at - including ultra-shallow if your lens is 3.5 or less. ;)


.
 
Last edited:
Thanks for your detailed guide. I have the original Canon breech-mount FD lenses (mechanically a joy, optically still quite good), so I'm assuming the first step is to remove the two tiny Phillips head screws from the knurled breech-mount ring, then pull the ring off to get at the "innards" as you described. Correct?
 
That sounds right. I thought there were more though. <shrug> I know when I'm in there. If you spend some time looking at it it's fairly obvious which screws you need to remove in order to lift off the mount. Just take pics as you go and everything will be OK.
 
One ther thing to be careful of. If your adapter has aperture open/close on it, make sure that it is set on "open" before you attach the lens to the adapter. If you have it set to "close", then then the pin in the adapter will be on the wrong side of the aperture lever and the lens will always be fully open. In some cases you may not even get the lens on.
 
You must log in or register to reply here.
Back
Top