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Archive 2009 · Problem with FD lens

synthesist
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p.1 #1 · p.1 #1 · Problem with FD lens

I picked up a cheap FD lens on ebay for about $5. I wanted to learn lens conversion on something small, before I moved up to the better lenses.

It just arrived, and (surprise!) there seems to be some sort of problem with it. The aperture do not seem to move when turn the aperture ring.

The levers on the back also seem to have no effect.

I read somewhere that FD lenses won't allow an aperture change unless they're mounted on a body, or the small pin in the back is pressed.

Maybe I'm doing this wrong.

Can anyone with experience add their insight into this?

http://www.eltongjata.com/images/sharing/lenses/IMG_4917.jpg

http://www.eltongjata.com/images/sharing/lenses/IMG_4922.jpg

Nov 28, 2009 at 03:37 PM

m-a-x
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p.1 #2 · p.1 #2 · Problem with FD lens

Hello Synthesist!
Try the toothpick trick: http://www.hv20.com/showthread.php?t=25305
If it doesn't work I would dismantle it neverteless, and try the last remaining lever.
Good luck!

Nov 28, 2009 at 04:28 PM

wickerprints
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p.1 #3 · p.1 #3 · Problem with FD lens

From your description, there is nothing wrong with the lens. The mechanical aperture controls do not operate when the lens is not mounted on a body. This is a design characteristic of the FD mount.

One of the levers will move freely. The other is locked.

As has been pointed out, it is possible to "trick" the mount and operate the diaphragm manually.

Nov 28, 2009 at 05:42 PM

Ed Sawyer
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p.1 #4 · p.1 #4 · Problem with FD lens

Canon FD is probably the hardest mount to learn on when it comes to converting lenses. Fabrication is almost always required. Minolta MD would be much easier to learn on.

-Ed

Nov 28, 2009 at 07:34 PM

synthesist
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p.1 #5 · p.1 #5 · Problem with FD lens

Thing is: both rings are free already. The aperture ring isn't locked. It rotates freely. But the blades don't move.

Does anyone have any tutorials on lens conversions?
They don't even have to be fd specific.

Nov 29, 2009 at 01:59 AM

wickerprints
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p.1 #6 · p.1 #6 · Problem with FD lens

synthesist wrote:
Thing is: both rings are free already. The aperture ring isn't locked. It rotates freely. But the blades don't move.

Does anyone have any tutorials on lens conversions?
They don't even have to be fd specific.

The aperture and focus rings are always free to rotate. But it's not the aperture ring that moves the diaphragm. It is the larger of the two levers on the rear that actually moves the diaphragm. All the aperture ring does is tell the lens how far to stop down.

The tip that was provided in m-a-x's post works. The unmounted lens is basically in a locked-down state, where you can turn the rings however you wish but it will do nothing to the diaphragm. It is in the process of mounting the lens that the sub-barrel rotates and frees the levers on the rear to move. There are two small locking pins that become recessed when the lens is mated to a FD camera mount. Then, when the outer barrel is turned, the sub-barrel rotates relative to the outer barrel and permits the levers to operate. The large lever is what engages the diaphragm. The small lever's position is determined by the aperture ring.

Just go to the link provided in the earlier post and follow the instructions. It will show you how the FD mount works. It is a very unusual design.

Incidentally, the image of the lens you provided does not look like it is an actual Canon FD lens, but a third-party FD lens. Am I correct?

Nov 29, 2009 at 02:52 AM

synthesist
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p.1 #7 · p.1 #7 · Problem with FD lens

Yes that is correct. It is a Chinar 28mm f2.8.

And it also only has one pin as opposed to the two. I'm going to give this a shot this morning, hope I can get it working.

Nov 29, 2009 at 11:42 AM

synthesist
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p.1 #8 · p.1 #8 · Problem with FD lens

One last question:

I'm trying to follow the instructions on the link above with no success.

The first two steps aren't working.

Clockwise pressure on the two little knobs isn't rotating anything. And the pin refuses to go down.

Should the lens be on A for this to work?

Nov 29, 2009 at 11:52 AM

cogitech
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p.1 #9 · p.1 #9 · Problem with FD lens

I've never been successful in getting the aperture to work by turning the aperture ring on an unconverted, unmounted Canon FD. This is due to the facts listed above; they are designed that way.

I ignore this, rip the old mount off, find the actual aperture mechanism inside and then figure out how to link it to the aperture ring. See the levers and springs and crap on the rear end of the lens? Once converted, all that stuff goes in the garbage.

This is one of the main FD conversion challenges, and one of the main reasons why Ed has recommended starting with an easier project.

I do wish you luck, however. You'll need some.

Nov 29, 2009 at 12:28 PM

AhamB
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p.1 #10 · p.1 #10 · Problem with FD lens

I managed to get the aperture working on my nFD 50/3.5 macro, by keeping the two pins pressed in and then turning the notch that's at the red dot clockwise (this is a bit awkard because you really need 3 hands for this unless you manage to press both pins with two tools in one hand -- which I did). This way I'm doing the same thing as an FD rear lenscap or body mount is doing (engaging the aperture).

It looks like you're doing it the wrong way round, Synthesist; the two pins must be pressed in and then the notch at the red dot is unlocked to move clockwise.

Edited on Nov 30, 2009 at 10:43 AM · View previous versions

Nov 29, 2009 at 03:50 PM

synthesist
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p.1 #11 · p.1 #11 · Problem with FD lens

There appear to be some differences in the lens I have in my hands then.

There is only 1 pin instead of 2.

There are two separate rings, one seems to raise and lower the pin, and lock the bayonet, and the other is the aperture ring. These are visible in the photo.

None of the tips given above seem to be doing anything with this.
It's possible I'm just doing it wrong. But I think I'm just going to tear into it.

I'll post some pics later on in the week if anyone is interested.

Nov 30, 2009 at 01:22 AM

AhamB
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p.1 #12 · p.1 #12 · Problem with FD lens

Ok, you are right; I explained how to do it with a new FD mount style lens.
Here are the instructions for the old breech-lock FD mount:

The ring with the red dot is the breech-lock ring, which locks the lens to the camera mount (or extension tube/etc.).

You engage the aperture like this:

1. Press the pin to unlock the BL ring. It looks like it's the "pin" (at 9 o' clock in picture 1) just to the left of the flathead screw at the topside of the mount.
You'll hear a click and the BL ring should be able to move freely (but if you turn it clockwise it will lock again).

2. Then turn the BL ring anti-clockwise, as you would when mounting the lens. This enables the aperture to be engaged.

3. Then you can use the aperture ring and push the aperture lever (actuator) anti-clockwise to close the aperture.

Nov 30, 2009 at 10:41 AM

lorriman
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p.1 #13 · p.1 #13 · Problem with FD lens

If you are willing to cut up an FD back lens-cap you can trigger the mechanism with a slight turn, then take off the cap and the aperture blades move freely.

Dec 01, 2009 at 10:21 AM


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